Interlayer for laminated glass, and laminated glass

ABSTRACT

The present invention provides an interlayer film for a laminated glass which can suppress bubble formation and bubble growth in the laminated glass. An interlayer film  1  for a laminated glass includes a first layer  2  and a second layer  3  laminated on one face  2   a  of the first layer  2 . Each of the first layer  2  and the second layer  3  contains a polyvinyl acetal resin and a plasticizer. In the case of measuring viscoelasticity of a resin film (glass transition temperature: Tg(° C.)) formed from the first layer  2  or a resin film (glass transition temperature: Tg(° C.)) formed with 100 parts by weight of the polyvinyl acetal resin contained in the first layer  2  and 60 parts by weight of a plasticizer of triethylene glycol di-2-ethylhexanoate (3GO), the resin film has an elastic modulus of G′(Tg+80) at (Tg+80)° C. and an elastic modulus of G′(Tg+30) at (Tg+30)° C., and provides a ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of patent applicationSer. No. 13/514,933, filed on Jun. 5, 2012, which is a 371 applicationof Application No. PCT/JP2010/073742, filed on Dec. 28, 2010, which isbased on Japanese Application Nos. 2009-297512 and 2010-202840, filed onDec. 28, 2009 and Sep. 10, 2010, respectively, the entire contents ofwhich are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an interlayer film for a laminatedglass that has a multi-layer structure including at least two layers.More specifically, the present Invention relates to an interlayer filmfor a laminated glass, each layer of which contains a polyvinyl acetalresin and a plasticizer; and a laminated glass including the interlayerfilm for a laminated glass.

BACKGROUND ART

A laminated glass is a safety glass which, even when broken by impactfrom the outside, shatters into few flying glass fragments. For thisreason, a laminated glass is widely used for cars, rail cars, aircrafts,boats and ships, buildings, and the like. The laminated glass isproduced by sandwiching an interlayer film for a laminated glass betweena pair of glass plates.

Patent Document 1 provides one example of the interlayer film for alaminated glass; that is, Patent Document 1 teaches a sound insulationlayer that contains 100 parts by weight of a polyvinyl acetal resinhaving a degree of acetalization of 60 to 85 mol %, 0.001 to 1.0 part byweight of at least one metal salt of an alkali metal salt and analkaline earth metal salt, and 30 parts by weight or more of aplasticizer. This sound insulation layer alone can be used as aninterlayer film.

Patent Document 1 also teaches a laminated interlayer film in which thesound insulation layer and other layers are laminated. Each of the otherlayers laminated on the sound insulation layer contains 100 parts byweight of a polyvinyl acetal resin having a degree of acetalization of60 to 85 mol %, 0.001 to 1.0 part by weight of at least one metal saltof an alkali metal salt and an alkaline earth metal salt, and 30 partsby weight or less of a plasticizer.

Patent Document 1: JP 2007-070200 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

A laminated glass formed with use of the interlayer film of PatentDocument 1 unfortunately has insufficient sound insulation for soundwith a frequency of about 2000 Hz, and therefore tends to providedecreased sound insulation when the coincidence effect is observed.Also, the laminated glass sometimes provides insufficient soundinsulation at around 20° C.

Here, the coincidence effect refers to a phenomenon in which, uponincidence, of sound waves on a glass plate, traverse waves spread on theglass surface to resonate with the incidence sound, whereby the sound istransmitted.

In the case of forming a laminated glass with the laminated interlayerfilm in which a sound insulation layer and other layers are laminatedaccording to Patent Document 1, the sound insulation at around 20° C. isincreased to some extent. However, the laminated interlayer film,including the sound insulation layer, can cause bubble formation whenused for a laminated glass.

Meanwhile, considerations have been made in recent years to increase theamount of the plasticizer in the interlayer film for an increase in thesound insulation of a laminated glass. Increasing the amount of theplasticizer can improve the sound insulation of the laminated glass.However, the increase in the amount of the plasticizer sometimes causesbubble formation in the laminated glass.

The present invention aims to provide an interlayer film for a laminatedglass which can give a laminated glass capable of suppressing bubbleformation and bubble growth; and a laminated glass using the interlayerfilm for a laminated glass.

Specifically, the present invention aims to provide an interlayer filmfor a laminated glass which can provide a laminated glass providingexcellent sound insulation; and a laminated glass using the interlayerfilm for a laminated glass.

Means for Solving the Problems

A broad aspect of the present invention is an interlayer film for alaminated glass, including a first layer that contains a polyvinylacetal resin and a plasticizer, and a second layer that contains apolyvinyl acetal resin and a plasticizer and is laminated on one face ofthe first layer, wherein in the case of measuring viscoelasticity of aresin film formed from the first layer, the resin film, having a glasstransition temperature of Tg(° C.), has an elastic modulus of G′(Tg+80)at (Tg+80)° C. and an elastic modulus of G′(Tg+30) at (Tg+30)° C., andprovides a ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher.

Another broad aspect of the present invention is an interlayer film fora laminated glass, including a first layer that contains a polyvinylacetal resin and a plasticizer, and a second layer that contains apolyvinyl acetal resin and a plasticizer and is laminated on one face ofthe first layer, wherein in the case of measuring viscoelasticity of aresin film formed with 100 parts by weight of the polyvinyl acetal resincontained in the first layer and 60 parts by weight of a plasticizer oftriethylene glycol di-2-ethylhexanoate (3GO), the resin film, having aglass transition temperature of Tg(° C.) has an elastic modulus ofG′(Tg+80) at (Tg+80)° C. and an elastic modulus of G′(Tg+30) at (Tg+30)°C., and provides a ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher.

In a specific aspect of the interlayer film for a laminated glassaccording to the present invention, the elastic modulus G′(Tg+30) is200,000 Pa or higher.

In another specific aspect of the interlayer film for a laminated glassaccording to the present invention, the polyvinyl acetal resin in thefirst layer has a degree of acetylation of 8 mol % or higher.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the polyvinyl acetal resin inthe first layer has a degree of acetylation of lower than 8 mol % and adegree of acetalization of 68 mol % or higher.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the polyvinyl acetal resin inthe first layer has a molecular-weight distribution (weight-averagemolecular weight Mw/number-average molecular weight Mn) of 6.5 or lower.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the polyvinyl acetal resin inthe first layer has a molecular-weight distribution (weight-averagemolecular weight Mw/number-average molecular weight Mn) of 2.5 to 3.2.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the first layer has 50 partsby weight or more of the plasticizer for each 100 parts by weight of thepolyvinyl acetal resin.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the first layer has 55 partsby weight or more of the plasticizer for each 100 parts by weight of thepolyvinyl acetal resin.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the polyvinyl acetal resin inthe first layer contains 30 mol % or lower of a hydroxyl group.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the film further includes athird layer that contains a polyvinyl acetal resin and a plasticizer andis laminated on the other face of the first layer.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, when the third layer is used,the polyvinyl acetal resin in the first layer has a degree ofacetylation of 8 mol % or higher.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, when the third layer is used,the polyvinyl acetal resin in the first layer has a degree ofacetylation of lower than 8 mol % and a degree of acetalization of 68mol % or higher.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, an amount of the plasticizerfor each 100 parts by weight of the polyvinyl acetal resin in the firstlayer is larger than an amount of the plasticizer for each 100 parts byweight of the polyvinyl acetal resin in each of the second layer and thethird layer.

The polyvinyl acetal resin in each of the first layer, the second layerand the third layer preferably includes a polyvinyl butyral resin. Theplasticizer in each of the first layer, the second layer and the thirdlayer preferably includes at least one compound selected from the groupconsisting of triethylene glycol di-2-ethylbutyrate, triethylene glycoldi-2-ethylhexanoate, and triethylene glycol di-n-heptanoate.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the polyvinyl acetal resin inthe first layer of the interlayer film for a laminated glass includes acarboxylic acid-modified polyvinyl acetal resin.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the first layer contains acompound that has a boron atom.

In a yet another specific aspect of the interlayer film for a laminatedglass according to the present invention, the compound that has a boronatom includes at least one compound selected from the group consistingof sodium tetraborate, potassium tetraborate, and boric acid.

A laminated glass according to the present invention is a laminatedglass that includes first laminated-glass component and secondlaminated-glass component, and an interlayer film sandwiched between thefirst laminated-glass component and the second laminated-glasscomponent, wherein the interlayer film is the interlayer film for alaminated glass formed according to the present invention.

Effect of the Invention

The interlayer film for a laminated glass according to the presentinvention includes a first layer that contains a polyvinyl acetal resinand a plasticizer, and a second layer that contains a polyvinyl acetalresin and a plasticizer and is laminated on one face of the first layer,and provides a ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher.Accordingly, the interlayer film, when used for a laminated glass, cansuppress bubble formation and bubble growth in the laminated glass.

In the case that the first layer contains 50 parts by weight or more ofthe plasticizer for each 100 parts by weight of the polyvinyl acetalresin, the sound insulation of the laminated glass can be sufficientlyincreased.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating aninterlayer film for a laminated glass according to one embodiment of thepresent invention.

FIG. 2 is a cross-sectional view schematically illustrating one exampleof a laminated glass including the interlayer film for a laminated glassillustrated in FIG. 1.

FIG. 3 is a view for explaining the relation between a loss tangent tanδ and the temperature and the relation between an elastic modulus G′ andthe temperature, which have resulted from measurement of theviscoelasticity of a resin film containing the polyvinyl acetal resin inthe first layer and triethylene glycol di-2-ethylhexanoate.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by means ofspecific Embodiments and Examples of the present invention, withreference to the drawings.

FIG. 1 is a cross-sectional view schematically illustrating aninterlayer film for a laminated glass according to one embodiment of thepresent invention.

An interlayer film 1 illustrated in FIG. 1 is provided with a firstlayer 2, a second layer 3 laminated on one face 2 a (first face) of thefirst layer 2, and a third layer 4 laminated on the other face 2 b(second face) of the first layer 2. The interlayer film 1 is used forforming a laminated glass. The interlayer film 1 is an interlayer filmfor a laminated glass. The interlayer film 1 is a laminated interlayerfilm.

The first layer 2 is arranged between the second layer 3 and the thirdlayer 4, that is, sandwiched between the second layer 3 and the thirdlayer 4. In the present embodiment, the first layer 2 is an intermediatelayer, and the second layer 3 and the third layer 4 are surface layers.Here, the second layer 3 and the third layer 4 may be intermediatelayers, and an additional interlayer film for a laminated glass may belaminated on each of outer surface 3 a of the second layer 3 and outersurface 4 a of the third layer 4.

Each of the first layer 2, the second layer 3 and the third layer 4preferably contains a polyvinyl acetal resin and a plasticizer.

The main feature of the present embodiment is that, in the case (testmethod A) of measuring viscoelasticity of a resin film A formed with 100parts by weight of the polyvinyl acetal resin contained in the firstlayer 2 and 60 parts by weight of a plasticizer of triethylene glycoldi-2-ethylhexanoate (3GO), the resin film A, having a glass transitiontemperature of Tg(° C.), has an elastic modulus of G′(Tg+80) at (Tg+80)°C. and an elastic modulus of G′(Tg+30) at (Tg+30)° C., and provides aratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher.

Also in the present embodiment, in the case (test method B) of measuringviscoelasticity of a resin film B formed from the first layer 2, theresin film B, having a glass transition temperature of Tg(° C.), has anelastic modulus of G′(Tg+80) at (Tg+80)° C. and an elastic modulus ofG′(Tg+30) at (Tg+30)° C., and provides a ratio (G′(Tg+80)/G′(Tg+30)) of0.65 or higher.

In test method B, the resin film B is formed from the first layer 2,i.e., the first layer 2 itself serves as the resin film B.

The resin film B is the first layer 2 that contains the polyvinyl acetalresin and the plasticizer at the same weight ratio as that in the firstlayer 2. In test method B, the elastic modulus G′(Tg+80) and the elasticmodulus G′(Tg+30) are preferably measured after the plasticizer ismigrated in the interlayer film 1 for a laminated glass. In test methodB, the elastic modulus G′(Tg+80) and the elastic modulus G′(Tg+30) arepreferably measured after the interlayer film 1 for a laminated glass isstored at the humidity of 30% (±3%) and the temperature of 23° C. forone month and the plasticizer is migrated in the interlayer film 1 for alaminated glass.

The present inventors have found that the plasticizer migrates betweenthe layers in a laminated interlayer film for a laminated glass, and asa result, a layer containing a large amount of the plasticizer isformed; for example, the plasticizer migrates from the second layer andthe third layer to the first layer, and the first layer turns out tocontain a large amount of the plasticizer. The present inventors havealso found that, formation of a layer containing a large amount of theplasticizer, i.e., a large amount of the plasticizer in the first layer,may easily cause bubble formation in a laminated glass including theinterlayer film for a laminated glass, and once bubbles is generated,the bubbles may grow with the generated bubbles as the core.

The present inventors have made various studies to suppress bubbleformation and bubble growth, and have found that bubble formation andbubble growth in a laminated glass can be sufficiently suppressed if theabove ratio (G′(Tg+80)/G′(Tg+30)) in test method A or test method B is0.65 or more. The bubble formation and bubble growth in the laminatedglass can be sufficiently suppressed even if the first layer contains alarge amount of the plasticizer. Therefore, the sound insulation of thelaminated glass can be increased. Particularly in the case that theinterlayer film for a laminated glass is used which has the second layerand the third layer laminated on the respective faces of the first layerproviding the ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher, the bubbleformation and bubble growth in the laminated glass can be furthersuppressed.

The ratio (G′(Tg+80)/G′(Tg+30)) is 0.65 or higher, and is preferably 1.0or lower. If the ratio (G′(Tg+80)/G′(Tg+30)) is 0.65 or higher, thebubble formation and bubble growth in the laminated glass can besufficiently suppressed even in the case that the laminated glass isstored under considerably severe conditions or stored for a long periodof time. Further, if the ratio (G′(Tg+80)/G′(Tg+30)) is within the rangeof the lower limit value to the upper limit value, the bubble formationand bubble growth in the laminated glass can be even more effectivelysuppressed even in the case that the laminated glass is stored underconsiderably severe conditions or stored for a long period of time. Theglass transition temperature Tg(° C.) represents the peak temperature ofthe loss tangent tan δ determined from the test results of the aboveviscoelasticity measurement.

The glass transition temperature Tg(° C.) represents the peaktemperature of the loss tangent tan δ determined from the test resultsof the above viscoelasticity measurement. In terms of furthersuppressing bubble formation and bubble growth in a laminated glass, theratio (G′(Tg+80)/G′(Tg+30)) is more preferably 0.7 or higher, morepreferably 0.95 or lower, still more preferably 0.75 or higher, andstill more preferably 0.9 or lower. Particularly, in the case that theratio (G′(Tg+80)/G′(Tg+30)) is controlled with the average degree ofpolymerization of the polyvinyl alcohol resin, bubble formation andbubble growth in the laminated glass can be sufficiently suppressed andthe sound insulation of the laminated glass can be further increased.The ratio (G′(Tg+80)/G′(Tg+30)) is preferably 0.65 or higher, morepreferably 0.66 or higher, still more preferably 0.67 or higher, andparticularly preferably 0.7 or higher. Further, the ratio is preferably0.82 or lower, and more preferably 0.8 or lower. If the ratio(G′(Tg+80)/G′(Tg+30)) is 0.82 or lower or 0.8 or lower, the interlayerfilm can be easily formed.

Examples of the method of setting the ratio (G′(Tg+80)/G′(Tg+30)) intest method A or test method B to 0.65 or higher include the method ofusing a polyvinyl alcohol resin having a comparatively high averagedegree of polymerization in synthesis of a polyvinyl acetal resin in thefirst layer 2; and the method of increasing the interaction between themolecules of the polyvinyl acetal resin in the first layer 2. Examplesof the method of increasing the interaction between the molecules of thepolyvinyl acetal resin in the first layer 2 include the method ofphysically crosslinking the molecules of the polyvinyl acetal resin, andthe method of chemically crosslinking the molecules. Preferable amongthese are the method of using a polyvinyl alcohol resin having acomparatively high average degree of polymerization in synthesis of apolyvinyl acetal resin in the first layer 2, and the method ofphysically crosslinking the molecules of the polyvinyl acetal resin inthe first layer 2, in terms of easy formation of the interlayer filmwith an extruder.

One example of the relation between the loss tangent tan δ and thetemperature and the relation between the elastic modulus G′ and thetemperature will be described by means of FIG. 3.

The loss tangent tan δ and the temperature are in the relation shown inFIG. 3. The temperature at the peak P of the loss tangent tan δ is theglass transition temperature Tg.

The glass transition temperature Tg of the elastic modulus G′ of thedashed line A2 illustrated in FIG. 3 is the same as the glass transitiontemperature Tg of the elastic modulus G′ of the solid line A1. Forexample, if the amount D of change in the elastic modulus G′(Tg+80)based on the elastic modulus G′(Tg+30) is smaller, bubble formation andbubble growth in the laminated glass can be more effectively suppressed.The amount D1 of change in the elastic modulus G′ of the solid line A1is smaller than the amount D2 of change in the elastic modulus G′ of thedashed line A2. Accordingly, bubble formation and bubble growth in thelaminated glass can be more effectively suppressed in the case that theresin film shows the elastic modulus G′ of the solid line A1 with acomparatively small amount D1 of change than in the case that the resinfilm shows the elastic modulus G′ of the dashed line A2 with acomparatively large amount D2 of change in FIG. 3.

The G′(Tg+30) is preferably 200,000 Pa or higher. The G′(Tg+30) is morepreferably 220,000 Pa or higher, still more preferably 230,000 Pa orhigher, and particularly preferably 240,000 Pa or higher. Further, theG′(Tg+30) is preferably 10 million Pa or lower, more preferably 5million Pa or lower, particularly preferably 1 million Pa or lower, moreparticularly preferably 500,000 Pa or lower, and still more particularlypreferably 300,000 Pa or lower. If the G′(Tg+30) is equal to or higherthan the above lowest value, bubble formation and bubble growth in thelaminated glass can be even more effectively suppressed.

The relation between the elastic modulus G′ and the temperature isgreatly influenced by the kind of the polyvinyl acetal resin,particularly the average degree of polymerization of the polyvinylalcohol resin used to obtain the polyvinyl acetal resin. The relation isnot much influenced by the kind of plasticizer or the amount of aplasticizer used if the plasticizer is a common one. The ratio(G′(Tg+80)/G′(Tg+30)) in the case of replacing the plasticizer 3GO witha plasticizer other than 3GO, such as a monobasic organic acid ester,particularly the ratio (G′(Tg+80)/G′(Tg+30)) in the case of usingplasticizers of triethylene glycol di-2-ethylbutyrate (3GH) andtriethylene glycol di-n-heptanoate (3G7), is not greatly different fromthe ratio (G′(Tg+80)/G′(Tg+30)) in the case of using 3GO. Also, in thecase that the amount of the plasticizer is 50 to 80 parts by weight foreach 100 parts by weight of the polyvinyl acetal resin, the values ofthe ratio (G′(Tg+80)/G′(Tg+30)) are not greatly different. The ratio(G′(Tg+80)/G′(Tg+30)) determined using a resin film that contains 100parts by weight of a polyvinyl acetal resin and 60 parts by weight of aplasticizer of triethylene glycol di-2-ethylhexanoate (3GO) is notlargely different from the ratio (G′(Tg+80)/G′(Tg+30)) determined usingthe first layer 2. Both of the ratio (G′(Tg+80)/G′(Tg+30)) determined intest method A and the ratio (G′(Tg+80)/G′(Tg+30)) determined in testmethod B are preferably 0.65 or higher, and it is more preferable thatthe ratio (G′(Tg+80)/G′(Tg+30)) determined in test method B is 0.65 orhigher.

If the first layer 2 has 50 parts by weight or more of the plasticizerfor each 100 parts by weight of the polyvinyl acetal resin, the soundinsulation of the laminated glass can be sufficiently increased.

Hereinafter, components contained in each of the first layer, the secondlayer and the third layer in the interlayer film 1 will be described indetail.

(Polyvinyl Acetal Resin)

In the case of containing a polyvinyl acetal resin and a plasticizer,each of the first layer 2, the second layer 3 and the third layer 4 inthe interlayer film 1 can show high adhesion. As a result, theinterlayer film 1 can provide even higher adhesion to thelaminated-glass components.

The polyvinyl acetal resin in the first layer 2 can be produced byacetalizing a polyvinyl alcohol resin with an aldehyde. The polyvinylacetal resin in the first layer 2 is a polyvinyl acetal resin obtainedby acetalizing a polyvinyl alcohol resin.

In terms of further suppressing bubble formation and bubble growth inthe laminated glass, the polyvinyl acetal resin in the first layer ispreferably obtained by acetalizing a polyvinyl alcohol resin having anaverage degree of polymerization exceeding 3000.

In terms of further suppressing bubble formation and bubble growth inthe laminated glass, the lowest average degree of polymerization of thepolyvinyl alcohol resin used to obtain the polyvinyl acetal resin in thefirst layer 2 is preferably 3010, preferably 3050, preferably 3500,preferably 3600, preferably 4000, and preferably 4050. The highestaverage degree is preferably 7000, preferably 6000, preferably 5000,preferably 4900, and preferably 4500. Particularly in terms of furthersuppressing bubble formation and bubble growth in the laminated glass,sufficiently increasing the sound insulation of the laminated glass, andeasily forming an interlayer film, the average degree of polymerizationof the polyvinyl alcohol resin used to obtain the polyvinyl acetal resinin the first layer 2 is preferably 3010 or higher, and more preferably3020 or higher. The average degree is also preferably 4000 or lower,more preferably lower than 4000, still more preferably 3800 or lower,particularly preferably 3600 or lower, and most preferably 3500 orlower.

The present inventors have also found that if the average degree ofpolymerization of the polyvinyl alcohol resin used to obtain thepolyvinyl acetal resin in the first layer is equal to or higher than theabove lowest degree, the ratio (G′(Tg+80)/G′(Tg+30)) in test method A ortest method B can easily be set to a value that satisfies the lowestvalue and the highest value.

In the present invention, the first layer 2 may contain, as thepolyvinyl acetal resin, only a polyvinyl acetal resin obtained byacetalizing a polyvinyl alcohol resin having an average degree ofpolymerization exceeding 3000, or may contain such a polyvinyl acetalresin obtained by acetalizing a polyvinyl alcohol resin having anaverage degree of polymerization exceeding 3000 in combination withanother polyvinyl acetal resin. The other polyvinyl acetal resin may bea polyvinyl acetal resin (hereinafter also referred to as a “polyvinylacetal resin Z”) obtained by acetalizing a polyvinyl alcohol resinhaving an average degree of polymerization of 3000 or lower. In thiscase, the minimum amount of the polyvinyl acetal resin obtained byacetalizing a polyvinyl alcohol resin having an average degree ofpolymerization exceeding 3000 relative to 100% by weight of the totalamount of the polyvinyl acetal resin obtained by acetalizing a polyvinylalcohol resin having an average degree of polymerization exceeding 3000and the polyvinyl acetal resin Z is preferably 5% by weight, morepreferably 50% by weight, still more preferably 70% by weight, andparticularly preferably 90% by weight. Also, the maximum amount thereofis preferably 100% by weight, and more preferably 95% by weight. Interms of further suppressing bubble formation and bubble growth in thelaminated glass, the other polyvinyl acetal resin is preferably apolyvinyl acetal resin obtained by acetalizing a polyvinyl alcohol resinhaving a degree of polymerization exceeding 3000.

The average degree of polymerization of the polyvinyl alcohol resin isdetermined by a method based on JIS K6726 “Testing Methods for Polyvinylalcohol”.

The polyvinyl acetal resin in each of the second layer 3 and the thirdlayer 4 can be produced by acetalizing a polyvinyl alcohol resin. Thelowest average degree of polymerization of the polyvinyl alcohol resinused to obtain the polyvinyl acetal resin in each of the second layer 3and the third layer 4 is preferably 200, more preferably 500, still morepreferably 1000, and particularly preferably 1500. The highest averagedegree is preferably 4000, more preferably 3500, still more preferably3000, and particularly preferably 2500. If the average degree ofpolymerization satisfies the lowest degree, the penetration resistanceof the laminated glass can be further increased. Further, if the averagedegree of polymerization satisfies the highest degree, formation of aninterlayer film is facilitated.

The average degree of polymerization of the polyvinyl alcohol resin usedto obtain the polyvinyl acetal resin in the first layer 2 is preferablyhigher than the average degree of polymerization of the polyvinylalcohol resin used to obtain the polyvinyl acetal resin in each of thesecond layer 3 and the third layer 4 by preferably 500 or more, morepreferably 800 or more, still more preferably 1000 or more, even morepreferably 1300 or more, and particularly preferably 1800 or more.

The polyvinyl alcohol resin is obtained by, for example, saponifyingpolyvinyl acetate. The degree of saponification of the polyvinyl alcoholresin is generally within the range of 70 to 99.9 mol %, preferablywithin the range of 75 to 99.8 mol %, and more preferably within therange of 80 to 99.8 mol %.

The aldehyde is not particularly limited. Generally, a C1 to C10aldehyde is suitably used as the above aldehyde. Examples of the C1 toC10 aldehyde include propionaldehyde, n-butyraldehyde, isobutyraldehyde,N-valeraldehyde, 2-ethylbutyraldehyde, n-hexyl aldehyde, n-octylaldehyde, n-nonyl aldehyde, n-decyl aldehyde, formaldehyde,acetaldehyde, and benzaldehyde. Particularly, n-butyraldehyde, n-hexylaldehyde, and n-valeraldehyde are preferable, and n-butyraldehyde ismore preferable. Each of the above aldehydes may be used alone, or twoor more of the aldehydes may be used in combination.

The polyvinyl acetal resin is preferably a polyvinyl butyral resin. Thepolyvinyl acetal resin in each of the first layer, the second layer andthe third layer preferably includes a polyvinyl butyral resin. Apolyvinyl butyral resin can be easily synthesized. Use of a polyvinylbutyral resin contributes to even more appropriate adhesion of theinterlayer film 1 to the laminated-glass components. Further, the useleads to a further increase in the properties such as light resistanceand weatherability.

The minimum hydroxyl content (the amount of the hydroxyl group) of thepolyvinyl acetal resin in the first layer 2, which is an intermediatelayer, is preferably 16 mol %, more preferably 18 mol %, still morepreferably 20 mol %, and particularly preferably 22 mol %. The maximumhydroxyl content is preferably 30 mol %, more preferably 29 mol %, stillmore preferably 27 mol %, and particularly preferably 25 mol %. If thehydroxyl content satisfies the preferable minimum amount, the firstlayer 2 can provide even higher adhesion. If the hydroxyl contentsatisfies the preferable maximum value, the laminated glass can provideeven higher sound insulation. Further, the interlayer film 1 can havehigher flexibility, and can therefore show even higher handlingproperties.

If the hydroxyl content of the polyvinyl acetal resin is low, thehydrophilicity of the polyvinyl acetal resin is low. Hence, the amountof the plasticizer used can be increased and, as a result, the soundinsulation of the laminated glass can be further increased. If thehydroxyl content of the polyvinyl acetal resin in the first layer 2 islower than the hydroxyl content of the polyvinyl acetal resin in each ofthe second layer 3 and the third layer 4, the amount of the plasticizerin the first layer 2 can be increased. In terms of a further increase inthe sound insulation of the laminated glass, the hydroxyl content of thepolyvinyl acetal resin in the first layer 2 is lower than the hydroxylcontent of the polyvinyl acetal resin in each of the second layer 3 andthe third layer 4 by preferably 2 mol % or more, more preferably 4 mol %or more, still more preferably 6 mol % or more, and particularlypreferably 8 mol % or more.

The minimum hydroxyl content of the polyvinyl acetal resin in each ofthe second layer 3 and the third layer 4, which are surface layers, ispreferably 26 mol %, more preferably 27 mol %, still more preferably 28mol %, particularly preferably 29 mol %, and more particularlypreferably 30 mol %. The maximum hydroxyl content is preferably 35 mol%, more preferably 34 mol %, still more preferably 33 mol %,particularly preferably 32 mol %, and most preferably 31.5 mol %. If thehydroxyl content satisfies the preferable minimum value, the interlayerfilm 1 can provide even higher adhesion. Further, if the hydroxylcontent satisfies the preferable maximum value, the interlayer film 1can have higher flexibility, and can therefore show even higher handlingproperties.

The hydroxyl content of the polyvinyl acetal resin is a molar fractiondetermined by dividing the amount of ethylene group having the hydroxylgroup bonded thereto by the total amount of the ethylene group in themain chain, represented in percentage (mol %). The amount of ethylenegroup having the hydroxyl group bonded thereto can be determined by, forexample, determining the amount of ethylene group having the hydroxylgroup bonded thereto in the polyvinyl acetal resin according to themethod based on JIS K6728 “Testing Methods for Polyvinyl butyral”.

The degree of acetylation (the amount of acetyl groups) of the polyvinylacetal resin in the first layer 2 is preferably 30 mol % or lower. Ifthe degree of acetylation exceeds 30 mol %, the reaction efficiency inproduction of a polyvinyl acetal resin may decrease.

The lowest degree of acetylation of the polyvinyl acetal resin in thefirst layer 2 is preferably 0.1 mol %, more preferably 0.5 mol %, andstill more preferably 0.8 mol %. The highest degree is preferably 24 mol%, more preferably 20 mol %, still more preferably 19.5 mol %, andparticularly preferably 15 mol %. The lowest degree of acetylation ofthe polyvinyl acetal resin in each of the second layer 3 and the thirdlayer 4 is preferably 0.1 mol %, more preferably 0.5 mol %, and stillmore preferably 0.8 mol %. The highest degree is preferably 20 mol %,more preferably 5 mol %, still more preferably 2 mol %, and particularlypreferably 1.5 mol %. If the degree of acetylation satisfies thepreferable lowest degree, the compatibility of the polyvinyl acetalresin and the plasticizer is further increased. If the degree ofacetylation satisfies the preferable highest degree, the moistureresistance of the interlayer film can be further increased. In terms ofa further increase in sound insulation of the laminated glass, if thedegree of acetalization of the polyvinyl acetal resin in the first layer2 is lower than the degree of acetalization of the polyvinyl acetalresin in each of the second layer 3 and the third layer 4, the degree ofacetylation of the polyvinyl acetal resin in the first layer 2 is higherthan the degree of acetylation of the polyvinyl acetal resin in each ofthe second layer 3 and the third layer 4 by preferably 3 mol % or more,more preferably 5 mol % or more, still more preferably 7 mol % or more,and particularly preferably 10 mol % or more.

The degree of acetylation is a molar fraction determined by dividing, bythe total amount of ethylene group in the main chain, a value resultingfrom subtracting the amount of ethylene group having the acetal groupbonded thereto and the amount of ethylene group having the hydroxylgroup bonded thereto from the total amount of ethylene group in the mainchain, represented in percentage (mol %). The amount of ethylene grouphaving the acetal group bonded thereto can be determined based on JISK6728 “Testing Methods for Polyvinyl butyral”, for example.

The lowest degree of acetalization of the polyvinyl acetal resin in thefirst layer 2 is preferably 50 mol %, more preferably 54 mol %, stillmore preferably 58 mol %, and particularly preferably 60 mol %. Thehighest degree is preferably 85 mol %, more preferably 80 mol %, andstill more preferably 79 mol %. The lowest degree of acetalization ofthe polyvinyl acetal resin in each of the second layer 3 and the thirdlayer 4 is preferably 60 mol %, more preferably 65 mol %, still morepreferably 66 mol %, and particularly preferably 67 mol %. The highestdegree is preferably 75 mol %, more preferably 72 mol %, still morepreferably 71 mol %, and particularly preferably 70 mol %. If the degreeof acetalization satisfies the preferable lowest degree, thecompatibility of the polyvinyl acetal resin and the plasticizer can befurther increased. If the degree of acetalization satisfies thepreferable highest degree, the reaction time required to produce apolyvinyl acetal resin can be shortened. In terms of a further increasein sound insulation of the laminated glass, if the absolute value of thedifference between the degree of acetylation of the polyvinyl acetalresin in the first layer 2 and the degree of acetylation of thepolyvinyl acetal resin in each of the second layer 3 and the third layer4 is 3 or less, the degree of acetalization of the polyvinyl acetalresin in the first layer 2 is higher than the degree of acetalization ofthe polyvinyl acetal resin in each of the second layer 3 and the thirdlayer 4 by preferably 3 mol % or more, more preferably 5 mol % or more,still more preferably 7 mol % or more, and particularly preferably 10mol % or more.

The degree of acetalization is a molar fraction determined by dividingthe amount of ethylene group having the acetal group bonded thereto bythe total amount of ethylene group in the main chain, represented inpercentage (mol %).

The degree of acetalization is calculated by first measuring the amountsof the acetyl group and the vinyl alcohol (hydroxyl content) based onJIS K6728 “Testing Methods for Polyvinyl butyral”, calculating the molarfraction from the measured amounts, and subtracting the amounts ofacetyl and vinyl alcohol from 100 mol %.

In terms of further suppressing bubble formation and bubble growth inthe laminated glass and further increasing the sound insulation of thelaminated glass, the polyvinyl acetal resin in the first layer 2 ispreferably a polyvinyl acetal resin having a degree of acetylation oflower than 8 mol % (hereinafter also referred to as “polyvinyl acetalresin A”) or a polyvinyl acetal resin having a degree of acetylation of8 mol % or higher (hereinafter also referred to as “polyvinyl acetalresin B”).

The degree a of acetylation of the polyvinyl acetal resin A is lowerthan 8 mol %, preferably 7.5 mol % or lower, preferably 7 mol % orlower, preferably 6 mol % or lower, and preferably 5 mol % or lower. Thedegree a of acetylation is preferably 0.1 mol % or higher, preferably0.5 mol % or higher, preferably 0.8 mol % or higher, preferably 1 mol %or higher, preferably 2 mol % or higher, preferably 3 mol % or higher,and preferably 4 mol % or higher. If the degree a of acetylation iswithin the range from the lowest value to the highest value, thecompatibility of the polyvinyl acetal resin and the plasticizer can befurther increased, and the sound insulation of the laminated glass cantherefore be further increased.

The lowest degree a of acetalization of the polyvinyl acetal resin A is68 mol %, more preferably 70 mol %, still more preferably 71 mol %, andparticularly preferably 72 mol %. The highest degree is preferably 85mol %, more preferably 83 mol %, still more preferably 81 mol %, andparticularly preferably 79 mol %. If the degree a of acetalization isequal to or higher than the lowest value, the sound insulation of thelaminated glass can be further increased. If the degree a ofacetalization is equal to or lower than the highest value, the reactiontime required to produce the polyvinyl acetal resin A can be shortened.

The hydroxyl content a of the polyvinyl acetal resin A is preferably 30mol % or lower, preferably 27.5 mol % or lower, preferably 27 mol % orlower, preferably 26 mol % or lower, preferably 25 mol % or lower,preferably 24 mol % or lower, and preferably 23 mol % or lower. Thehydroxyl content a is preferably 16 mol % or higher, preferably 18 mol %or higher, preferably 19 mol % or higher, and preferably 20 mol % orhigher. If the hydroxyl content a is equal to or lower than the highestvalue, the sound insulation of the laminated glass can be furtherincreased. If the hydroxyl content a is equal to or higher than thelowest value, the adhesion of the interlayer film can be furtherincreased.

The polyvinyl acetal resin A is preferably a polyvinyl butyral resin.

The degree b of acetylation of the polyvinyl acetal resin B is 8 mol %or higher, preferably 9 mol % or higher, preferably 10 mol % or higher,preferably 11 mol % or higher, and preferably 12 mol % or higher. Thedegree b of acetylation is preferably 30 mol % or lower, preferably 28mol % or lower, preferably 26 mol % or lower, preferably 24 mol % orlower, preferably 20 mol % or lower, and preferably 19.5 mol % or lower.If the degree b of acetylation is equal to or higher than the lowestvalue, the sound insulation of the laminated glass can be furtherincreased. If the degree b of acetylation is equal to or lower than thehighest value, the reaction time required to produce the polyvinylacetal resin B can be shortened. In terms of further shortening thereaction time required to produce the polyvinyl acetal resin B, thedegree b of acetylation of the polyvinyl acetal resin B is preferablylower than 20 mol %.

The degree b of acetalization of the polyvinyl acetal resin B is 50 mol% or higher, more preferably 52.5 mol % or higher, still more preferably54 mol % or higher, and particularly preferably 60 mol % or higher. Thedegree b of acetalization is preferably 80 mol % or lower, morepreferably 77 mol % or lower, still more preferably 74 mol % or lower,and particularly preferably 71 mol % or lower. If the degree b ofacetalization is equal to or higher than the lowest value, the soundinsulation of the laminated glass can be further increased. If thedegree b of acetalization is equal to or lower than the highest value,the reaction time required to produce the polyvinyl acetal resin B canbe shortened.

The hydroxyl content b of the polyvinyl acetal resin B is preferably 30mol % or lower, preferably 27.5 mol % or lower, preferably 27 mol % orlower, preferably 26 mol % or lower, and preferably 25 mol % or lower.The hydroxyl content b is preferably 18 mol % or higher, preferably 20mol % or higher, preferably 22 mol % or higher, and preferably 23 mol %or higher. If the hydroxyl content b is equal to or lower than thehighest value, the sound insulation of the laminated glass can befurther increased. If the hydroxyl content b is equal to or higher thanthe lowest value, the adhesion of the interlayer film can be furtherincreased.

The polyvinyl acetal resin B is preferably a polyvinyl butyral resin.

The polyvinyl acetal resin A and the polyvinyl acetal resin B each arepreferably obtained by acetalizing with an aldehyde a polyvinyl alcoholresin having an average degree of polymerization exceeding 3000. Thealdehyde is preferably a C1 to C10 aldehyde, and is more preferably a C4or C5 aldehyde. The lowest average degree of polymerization of thepolyvinyl alcohol resin is preferably 3010, preferably 3050, preferably3500, preferably 3600, preferably 4000, and preferably 4050. The highestaverage degree is preferably 7000, preferably 6000, preferably 5000,preferably 4900, and preferably 4500. The polyvinyl acetal resin in thefirst layer 2 is particularly preferably obtained by acetalizing apolyvinyl alcohol resin having an average degree of polymerizationexceeding 3000 and lower than 4000. Particularly, in terms of furthersuppressing bubble formation and bubble growth in the laminated glass,sufficiently increasing the sound insulation of the laminated glass, andeasily forming an interlayer film, the average degree of polymerizationof the polyvinyl alcohol resin used to obtain the polyvinyl acetal resinin the first layer 2 is preferably 3010 or higher, and more preferably3020 or higher. The average degree of polymerization is preferably 4000or lower, more preferably lower than 4000, still more preferably 3800 orlower, particularly preferably 3600 or lower, and most preferably 3500or lower.

The molecular-weight distribution (weight-average molecular weightMw/number-average molecular weight Mn) of the polyvinyl acetal resin inthe first layer 2 is generally 1.1 or higher, preferably 1.2 or higher,and more preferably 2 or higher. The molecular-weight distribution ispreferably 6.7 or lower, more preferably 6.5 or lower, and still morepreferably 3.4 or lower.

The lowest molecular-weight distribution of the polyvinyl acetal resinin the first layer 2 is preferably 1.2, more preferably 1.5, still morepreferably 2.0, and particularly preferably 2.5. The highestmolecular-weight distribution is preferably 5.5, more preferably 5,still more preferably 4.6, and particularly preferably 3.2. Themolecular-weight distribution of the polyvinyl acetal resin in the firstlayer 2 is particularly preferably 2.5 to 3.2. The molecular-weightdistribution represents the ratio of the weight-average molecular weightMw of the polyvinyl acetal resin in the first layer 2 to thenumber-average molecular weight Mn of the polyvinyl acetal resin in thefirst layer 2. The present inventors have also found that, if themolecular-weight distribution of the polyvinyl acetal resin in the firstlayer is within the range from the lowest value to the highest value oris 2.5 to 3.2, it is easy to set the ratio (G′(Tg+80)/G′(Tg+30)) in testmethod A or test method B to a value satisfying the above lowest valueand the highest value, and to more effectively suppress bubble formationand bubble growth in the laminated glass. Particularly, in terms of moreeffectively suppressing bubble formation and bubble growth in thelaminated glass and further increasing the sound insulation of thelaminated glass, it is preferable that the molecular-weight distributionof the polyvinyl acetal resin in the first layer 2 is 6.5 or lower, andthe amount of the plasticizer for each 100 parts by weight of thepolyvinyl acetal resin in the first layer 2 is 50 parts by weight ormore. Particularly in the case that the polyvinyl acetal resin in thefirst layer 2 contains the polyvinyl acetal resin B, it is preferablethat the molecular-weight distribution of the polyvinyl acetal resin Bis 6.5 or lower, and the amount of the plasticizer for each 100 parts byweight of the polyvinyl acetal resin in the first layer 2 is preferably55 parts by weight or more.

The weight-average molecular weight and the number-average molecularweight respectively represent the polystyrene-equivalent weight-averagemolecular weight and number-average molecular weight determined by gelpermeation chromatography (GPC). For example, in order to determine thepolystyrene-equivalent weight-average molecular weight andnumber-average molecular weight, GPC measurement of the polystyrenestandard samples the molecular weight of which are known is performed.The polystyrene standard samples used (“Shodex Standard SM-105” and“Shodex Standard SH-75” produced by Showa Denko K.K.) are 14 sampleshaving weight-average molecular weights of 580, 1260, 2960, 5000, 10100,21000, 28500, 76600, 196000, 630000, 1130000, 2190000, 3150000, and3900000. An approximation straight line, obtained by plotting themolecular weights relative to the elution times shown by the peak topsof the respective standard sample peaks, can be used as a calibrationcurve. The surface layers (the second layer 3 and the third layer 4) andthe intermediate layer (the first layer 2) are separated from thelaminated interlayer film that has been left to stand in a constanttemperature and humidity room (humidity: 30% (±3%), temperature: 23° C.)for one month. The separated first layer (intermediate layer) isdissolved in tetrahydrofuran (THF) so that 0.1% by weight of a solutionis prepared. The solution is analyzed with a GPC device to determine theweight-average molecular weight and the number-average molecular weightthereof. The GPC device used to determine the weight-average molecularweight and the number-average molecular weight may be a GPC device(produced by Hitachi High-technologies Corporation, “RI: 12490,autosampler: L-2200, pump: L-2130, column oven: L-2350, column:GL-A120-S and GL-A100MX-S in series”) to which a light scatteringdetector for GPC (“Model 270 (RALS+VISCO)” produced by VISCOTEK) isconnected.

In terms of further suppressing bubble formation and bubble growth inthe laminated glass and obtaining a laminated glass with excellent soundinsulation, the polyvinyl acetal resin in the first layer 2 ispreferably a carboxylic acid-modified polyvinyl acetal resin, and morepreferably a carboxylic acid-modified polyvinyl butyral resin. Use of acarboxylic acid-modified polyvinyl acetal resin makes it easy to set theratio (G′(Tg+80)/G′(Tg+30)) in test method A or test method B to a valuethat satisfies the lowest value and the highest value. The carboxylicacid-modified polyvinyl acetal resin contains ethylene group having anacetal group, ethylene group having an acetyl group, and ethylene grouphaving a hydroxyl group. Examples of the carboxylic acid includeunsaturated dicarboxylic acids and unsaturated tricarboxylic acids. Thecarboxylic acid is preferably an unsaturated dicarboxylic acid such asmaleic acid and itaconic acid. If the total amount of the ethylene grouphaving an acetal group, the ethylene group having an acetyl group, theethylene group having a hydroxyl group, and the ethylene group modifiedwith the above carboxylic acid is set to 100 mol %, the proportion ofthe ethylene group modified with the above carboxylic acid is preferablyhigher than 0 mol % and 10 mol % or lower. The highest proportion of theethylene group modified with the above carboxylic acid is preferably 9mol %, preferably 8 mol %, preferably 7 mol %, preferably 6 mol %,preferably 5 mol %, preferably 4 mol %, preferably 3 mol %, andpreferably 2 mol %.

(Plasticizer)

The plasticizer in each of the first layer 2, the second layer 3 and thethird layer 4 is not particularly limited. The plasticizer may be apublicly known plasticizer. One plasticizer may be used or two or moreplasticizers may be used in combination as the above plasticizer.

Examples of the plasticizer include organic ester plasticizers such as amonobasic organic acid ester and a polybasic organic acid ester, andphosphorus plasticizers such as an organic phosphorus acid plasticizerand an organic phosphorous acid plasticizer. Among these, an organicester plasticizer is preferable. The plasticizer is preferably a liquidplasticizer.

Examples of the monobasic organic acid ester include, but notparticularly limited to, a glycol ester obtained through the reaction ofglycol and a monobasic organic acid, and an ester of a monobasic organicacid and triethylene glycol or tripropylene glycol. Examples of theglycol include triethylene glycol, tetraethylene glycol, andtripropylene glycol. Examples of the monobasic organic acid includebutanoic acid, isobutyric acid, caproic acid, 2-ethylbutanoic acid,heptylic acid, n-octyl acid, 2-ethylhexyl acid, n-nonylic acid, anddecylic acid.

Examples of the polybasic organic acid ester include, but notparticularly limited to, ester compounds such as one of a polybasicorganic acid and a C4 to C8 straight or branched chain alcohol. Examplesof the polybasic organic acid include adipic acid, sebacic acid, andazelaic acid.

Examples of the organic ester plasticizer include, but not particularlylimited to, triethylene glycol di-2-ethylbutyrate, triethylene glycoldi-2-ethylhexanoate, triethylene glycol dicaprylate, triethylene glycoldi-n-octanoate, triethylene glycol di-n-heptanoate, tetraethylene glycoldi-n-heptanoate, dibutyl sebacate, dioctylazelate, dibutylcarbitoladipate, ethylene glycol di-2-ethylbutyrate, 1,3-propylene glycoldi-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate, diethyleneglycol di-2-ethylbutyrate, diethylene glycol di-2-ethylhexanoate,dipropylene glycol di-2-ethylbutyrate, triethylene glycoldi-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate,diethylene glycol dicaprylate, dihexyl adipate, dioctyl adipate,hexylcyclohexyl adipate, a mixture of heptyl adipate and nonyl adipate,diisononyl adipate, diisodecyl adipate, heptyl nonyl adipate, dibutylsebacate, oil-modified alkyd sebacate, and a mixture of phosphate andadipate. An organic ester plasticizer other than these may be used. Anadipate other than the above adipates may be used.

Examples of the organic phosphoric acid plasticizer include, but notparticularly limited to, tributoxyethyl phosphate, isodecyl phenylphosphate, and triisopropyl phosphate.

The plasticizer is preferably a diester plasticizer represented by thefollowing formula (1). The use of a diester plasticizer can furtherincrease the sound insulation of the laminated glass.

In formula (1), R1 and R2 each represent a C5 to C10 organic group, R3represents an ethylene group, an isopropylene group, or an n-propylenegroup, and p represents an integer of 3 to 10. R1 and R2 in formula (1)each preferably represent a C6 to C10 organic group.

The plasticizer preferably contains at least one compound selected fromthe group consisting of triethylene glycol di-2-ethylbutyrate (3GH),triethylene glycol di-2-ethylhexanoate (3GO) and triethylene glycoldi-n-heptanoate (3G7), and more preferably contains triethylene glycoldi-2-ethylhexanoate. The plasticizer in each of the first layer, thesecond layer and the third layer preferably includes at least onecompound selected from the group consisting of triethylene glycoldi-2-ethylbutyrate, triethylene glycol di-2-ethylhexanoate, andtriethylene glycol di-n-heptanoate. Use of these preferable plasticizerscan further increase the sound insulation of the laminated glass.

The amount of the plasticizer in each layer of the interlayer film 1 isnot particularly limited.

In terms of sufficiently increasing the sound insulation of thelaminated glass, the amount of the plasticizer for each 100 parts byweight of the polyvinyl acetal resin in the first layer 2 is preferably40 parts by weight or more. Even if the amount of the plasticizer in thefirst layer 2 is large, bubble formation and bubble growth in thelaminated glass can be suppressed because the first layer 2 is formed toprovide a ratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher.

The minimum amount of the plasticizer for each 100 parts by weight ofthe polyvinyl acetal resin in the first layer 2 is preferably 45 partsby weight, more preferably 50 parts by weight, particularly preferably55 parts by weight, and most preferably 60 parts by weight. The maximumamount is preferably 80 parts by weight, more preferably 78 parts byweight, still more preferably 75 parts by weight, and particularlypreferably 70 parts by weight. If the amount of the plasticizersatisfies the preferable minimum amount, the penetration resistance ofthe laminated glass can be further increased. A larger amount of theplasticizer in the first layer 2 leads to even higher sound insulationof the laminated glass. If the amount of the plasticizer satisfies thepreferable maximum amount, the interlayer film can provide even highertransparency.

The minimum amount of the plasticizer for each 100 parts by weight ofthe polyvinyl acetal resin in each of the second layer 3 and the thirdlayer 4 is preferably 25 parts by weight, more preferably 30 parts byweight, and still more preferably 35 parts by weight. The maximum amountis preferably 50 parts by weight, more preferably 45 parts by weight,still more preferably 40 parts by weight, and particularly preferably 39parts by weight. If the amount of the plasticizer satisfies thepreferable minimum amount, the adhesion of the interlayer film isincreased, which leads to a further increase in the penetrationresistance of the laminated glass. If the amount of the plasticizersatisfies the preferable maximum amount, the transparency of theinterlayer film can be further increased.

In terms of further increasing the sound insulation of the laminatedglass, the amount of the plasticizer for each 100 parts by weight of thepolyvinyl acetal resin in the first layer 2 is preferably larger thanthe amount of the plasticizer for each 100 parts by weight of thepolyvinyl acetal resin in each of the second layer 3 and the third layer4. In terms of further increasing the sound insulation of the laminatedglass, the amount of the plasticizer for each 100 parts by weight of thepolyvinyl acetal resin in the first layer 2 is larger than the amount ofthe plasticizer for each 100 parts by weight of the polyvinyl acetalresin in each of the second layer 3 and the third layer 4 by preferably5 parts by weight or more, more preferably 10 parts by weight or more,still more preferably 12 parts by weight or more, and particularlypreferably 15 parts by weight or more.

(Other Components)

In terms of further suppressing bubble formation and bubble growth inthe laminated glass and obtaining a laminated glass with excellent soundinsulation, the first layer preferably contains a compound that containsa boron atom. Examples of the compound that contains a boron atominclude, but not particularly limited to, tetraborates and boric acid.Examples of the tetraborates include sodium tetraborate and potassiumtetraborate. The use of a compound that contains a boron atom makes iteasy to set the ratio (G′(Tg+80)/G′(Tg+30)) in test method A or testmethod B to a value satisfying the minimum amount and the maximumamount.

The minimum amount of the compound that contains a boron atom for each100 parts by weight of the polyvinyl acetal resin in the first layer 2is preferably 0.01 parts by weight, more preferably 0.05 parts byweight, and still more preferably 0.1 parts by weight. The maximumamount is preferably 5 parts by weight, more preferably 1 part byweight, and still more preferably 0.5 parts by weight. If the amount ofthe compound that contains a boron atom satisfies the preferable minimumamount, it is easy to set the ratio (G′(Tg+80)/G′(Tg+30)) in test methodA or test method B to a value satisfying the minimum amount and themaximum amount. If the amount of the compound that contains a boron atomsatisfies the preferable maximum amount, the transparency of thelaminated glass can be further increased.

Each of the first layer 2, the second layer 3 and the third layer 4 ofthe interlayer film 1 may contain additives such as an ultraviolet rayabsorbent, an antioxidant, a light stabilizer, a flame retardant, anantistatic agent, a pigment, a dye, an adhesion regulator, a moistureresistant agent, a fluorescent bleach, and an infrared absorbent.

(Method of Producing Interlayer Film for Laminated Glass, and LaminatedGlass)

Examples of the method of producing an interlayer film for a laminatedglass according to the present invention include, but not particularlylimited to, a method of forming each of the first layer 2, the secondlayer 3 and the third layer 4 using resin compositions each containingthe polyvinyl acetal resin and the plasticizer and, for example,laminating the second layer 3, the first layer 2, and the third layer 4in the stated order; and a method of co-extruding these resincompositions with an extruder to laminate the second layer 3, the firstlayer 2, and the third layer 4 in the stated order. In terms ofexcellent production efficiency of the interlayer film, the second layer3 and the third layer 4 preferably contain the same polyvinyl acetalresin. More preferably, the second layer 3 and the third layer 4 containthe same polyvinyl acetal resin and the same plasticizer. Still morepreferably, the second layer 3 and the third layer 4 are formed from thesame resin composition.

Each interlayer film for a laminated glass according to the presentinvention is used to obtain a laminated glass.

FIG. 2 is a cross-sectional view schematically illustrating one exampleof a laminated glass using the interlayer film 1 in FIG. 1.

A laminated glass 11 in FIG. 2 is provided with a first laminated-glasscomponent 12, a second laminated-glass component 13, and the interlayerfilm 1. The interlayer film 1 is sandwiched between the firstlaminated-glass component 12 and the second laminated-glass component13.

The first laminated-glass component 12 is laminated on an outer surface3 a of the second layer 3. The second laminated-glass component 13 islaminated on an outer surface 4 a of the third layer 4. Therefore, thelaminated glass 11 has the first laminated-glass component 12, thesecond layer 3, the first layer 2, the third layer 4, and the secondlaminated-glass component 13 which are laminated in the stated order.

Examples of the first laminated-glass component 12 and the secondlaminated-glass component 13 include glass plates and PET (polyethyleneterephthalate) films. The laminated glass encompasses not only alaminated glass having an interlayer film sandwiched between two glassplates but also a laminated glass having an interlayer film sandwichedbetween a glass plate and a PET film. A laminated glass is a laminatedproduct provided with glass plate(s). A laminated glass preferably hasat least one glass plate.

Examples of the glass plate include inorganic glasses and organicglasses. Examples of the inorganic glass include float plate glass, heatabsorbing plate glass, heat reflecting glass, polished plate glass,molded plate glass, wire plate glass, and lined plate glass. The organicglass is a synthetic resin glass substituted for inorganic glass.Examples of the organic glass include polycarbonate plates andpoly(meth)acrylic resin plates. Examples of the poly(meth)acrylic resinplate include polymethyl (meth)acrylate plates.

In terms of further increasing the penetration resistance of thelaminated glass 11, the minimum thickness of the interlayer film 1 ispreferably 0.05 mm, and more preferably 0.25 mm. The maximum thicknessis preferably 3 mm, and more preferably 1.5 mm. If the thickness of theinterlayer film 1 satisfies the preferable minimum thickness and thepreferable maximum thickness, the penetration resistance and thetransparency of the laminated glass can be further increased. Theminimum thickness of the first layer 2 is preferably 0.01 mm, morepreferably 0.04 mm, and still more preferably 0.07 mm. The maximumthickness is preferably 0.3 mm, more preferably 0.2 mm, still morepreferably 0.18 mm, and particularly preferably 0.16 mm. If thethickness of the first layer 2 satisfies the minimum thickness, thesound insulation of the laminated glass can be further increased. If thethickness satisfies the maximum thickness, the transparency of thelaminated glass can be further increased. The minimum thickness of eachof the second layer 3 and the third layer 4 is preferably 0.1 mm, morepreferably 0.2 mm, still more preferably 0.25 mm, and particularlypreferably 0.3 mm. The maximum thickness is preferably 0.6 mm, morepreferably 0.5 mm, still more preferably 0.45, and particularlypreferably 0.4 mm. If the thickness of each of the second layer 3 andthe third layer 4 satisfies the minimum thickness, the penetrationresistance of the laminated glass can be further increased. If thethickness satisfies the maximum thickness, the transparency of thelaminated glass can be further increased. A smaller ratio of thethickness of the first layer 2 to the thickness of the interlayer film 1((thickness of the first layer 2)/(thickness of the interlayer film 1))and a larger amount of the plasticizer in the first layer 2 tend tocause bubble formation and grow the bubbles in the laminated glass more.Particularly in the case that the ratio in the interlayer film 1 is 0.05to 0.35 and the amount of the plasticizer for each 100 parts by weightof the polyvinyl acetal resin in the first layer 2 is 55 parts by weightor more, the bubble formation and bubble growth in the laminated glassincluding the interlayer film for a laminated glass according to thepresent invention can be sufficiently suppressed and the soundinsulation of the laminated glass can be further increased. The minimumvalue of the ratio (thickness of the first layer 2)/(thickness of theinterlayer film 1)) is preferably 0.06, more preferably 0.07, still morepreferably 0.08, and particularly preferably 0.1. The maximum value ispreferably 0.3, more preferably 0.25, still more preferably 0.2, andparticularly preferably 0.15.

The thickness of each of the first laminated-glass component 12 and thesecond laminated-glass component 13 is preferably 0.5 mm or larger, andmore preferably 1 mm or larger. The thickness is also preferably 5 mm orsmaller, and more preferably 3 mm or smaller. If the laminated-glasscomponents 12 and 13 are glass plates, the thickness of each glass plateis preferably within the range of 1 to 3 mm. If the laminated-glasscomponents 12 and 13 are PET films, the thickness of each PET film ispreferably within the range of 0.03 to 0.5 mm.

The method of producing a laminated glass 11 is not particularlylimited. For example, sandwiching the interlayer film 1 between thefirst laminated-glass component 12 and the second laminated-glasscomponent 13, and then removing the air remaining between the interlayerfilm 1 and the first laminated-glass component 12 and the secondlaminated-glass component 13 by pressing the resulting product bypressure rollers, or putting the product in a rubber bag forvacuum-sucking. Then, the product is pre-bonded at about 70° C. to 110°C. to obtain a laminate. Next, the laminate is put into an autoclave oris pressed, so as to be pressure-bonded at about 120° C. to 150° C. and1 to 1.5 MPa. Thus, the laminated glass 11 can be obtained.

The laminated glass 11 can be widely used for cars, rail cars,aircrafts, boats and ships, buildings, and the like. The laminated glass11 can be used in applications other than these uses. For example, thelaminated glass 11 can be used for windshields, side glass, rear glass,and roof glass of cars.

Hereinafter, the present invention will be described in more detailbased on Examples. The present invention is not limited to theseExamples.

EXAMPLE 1 (1) Production of Laminated Interlayer Film

To 100 parts by weight of polyvinyl butyral resin A (hydroxyl content:23.5 mol %, degree of acetylation: 12.5 mol %, degree of butyralization:64 mol %) obtained by butyralizing with n-butyl aldehyde a polyvinylalcohol resin having an average degree of polymerization of 3050, 60parts by weight of a plasticizer of triethylene glycoldi-2-ethylhexanoate (3GO) was added. The mixture was sufficientlykneaded by a mixing roll, so that a resin composition for anintermediate layer was obtained.

To 100 parts by weight of polyvinyl butyral resin B (hydroxyl content:30.4 mol %, degree of acetylation: 0.8 mol %, degree of butyralization:68.8 mol %) obtained by butyralizing with n-butyl aldehyde a polyvinylalcohol resin having an average degree of polymerization of 1700, 37.5parts by weight of a plasticizer of triethylene glycoldi-2-ethylhexanoate (3GO) was added. The mixture was sufficientlykneaded by a mixing roll, so that a resin composition for a surfacelayer was obtained.

The resin composition for an intermediate layer and the resincomposition for a surface layer were co-extruded by an extruder, wherebya laminated interlayer film in which a surface layer (thickness: 350μm), an intermediate layer (thickness: 100 μm), and a surface layer(thickness: 350 μm) were laminated in the stated order.

(2) Production of Laminated Glass Used for Penetration Resistance Test

The obtained laminated interlayer film was cut into a size of 30 cm(length)×30 cm (width). Next, the laminated interlayer film wassandwiched between two transparent float glasses (30 cm (length)×30 cm(width)×2.5 mm (thickness)), and thereby a laminate was obtained. Thelayered product was put into a rubber bag and deaerated for 20 minutesat the degree of vacuum of 2.6 kPa, and the deaerated product was putinto an oven to further stand at 90° C. for 30 minutes forvacuum-pressing, so that the laminate was pressure-bonded in advance.The preliminary pressure-bonded laminate was pressure-bonded in anautoclave at 135° C. and a pressure of 1.2 MPa for 20 minutes. Thereby,a laminated glass to be used for a penetration resistance test wasobtained.

(3) Production of Laminated Glass Used for Sound Insulation Measurement

A laminated glass to be used for sound insulation measurement wasproduced by the same procedure as that for obtaining a laminated glassto be used for a penetration resistance test, except that the laminatedinterlayer film was cut into a size of 30 cm (length)×2.5 cm (width) andeach of the transparent float glasses used had a size of 30 cm(length)×2.5 cm (width)×2.5 mm (thickness).

(4) Production of Laminated Glass Used for Bubble Formation TestLaminated Glass Used for Bubble Formation Test in Test Method A)

The obtained laminated interlayer film was cut into a size of 30 cm(length)×15 cm (width), and the cut-out film was left to stand at 23° C.for 10 hours. Here, both faces of the obtained laminated interlayer filmwere embossed, and the ten-point height of irregularities of theembossing was 30 μm. In the cut-out laminated interlayer film, a throughhole of 6 mm in diameter was formed at four points, each of which was ata distance of 8 cm inward from an end of the laminated interlayer filmin the lengthwise direction and 5 cm inward from an end of the laminatedinterlayer film in the transverse direction. As a result, a laminatedinterlayer film having through holes was obtained.

The laminated interlayer film having through holes was sandwichedbetween two transparent float glasses (30 cm (length)×15 cm (width)×2.5mm (thickness)), so that a laminate was obtained. The periphery of thelaminate was sealed 2 cm from the end with a sealing agent by thermalfusion bonding to encapsulate the air remaining in the embossed partsand in the through holes. The laminate was pressure-bonded at 135° C.and a pressure of 1.2 MPa for 20 minutes, so that the remaining air wasdissolved into the laminated interlayer film. Thereby, a laminated glassto be used for a bubble formation test was obtained.

(Laminated Glass Used for Bubble Formation Test in Test Method B)

A laminated glass to be used for the bubble formation test in testmethod B was obtained by the same procedure as that for obtaining alaminated glass to be used for the bubble formation test in test methodA, except that no through hole was formed in the laminated interlayerfilm.

Examples 2 to 46 and Comparative Examples 1 to 12

An interlayer film and a laminated glass were produced by the sameprocedure as that for Example 1, except that the compositions for thefirst layer, the second layer and the third layer and the average degreeof polymerization of the polyvinyl alcohol resin used to obtain thepolyvinyl acetal resin for the first layer were changed to the valuesshown in the following Tables 1 to 5.

In each of Examples 34 to 36, sodium tetraborate in the amount shown inTable 4 was added for each 100 parts by weight of the polyvinyl acetalresin in preparation of a resin composition for an intermediate layer.In Example 37, an interlayer film and a laminated glass were produced bythe same procedure as that for Example 1, except that the resincomposition for an intermediate layer contained a carboxylicacid-modified polyvinyl butyral resin (average degree of polymerization:1800, hydroxyl content: 21.3 mol %, degree of acetylation: 12.6 mol %,degree of butyralization: 64.9 mol %, proportion of carboxylic acidmodification: 1.2 mol %) in place of a polyvinyl butyral resin, and theformulations for the first layer, the second layer and the third layerwere changed to the ones shown in Table 4. The polyvinyl butyral resinscontained in the respective resin compositions for a surface layer inExamples 2 to 46 and Comparative Examples 1 to 12 each were obtained byacetalizing a polyvinyl alcohol resin having an average degree ofpolymerization of 1700.

(Evaluation) (1) Sound Insulation

The laminated glass was vibrated with a vibration generator for adumping test (“Vibration generator G21-005D” produced by Shinken Co.,Ltd.). The vibration characteristics obtained thereby were amplifiedwith a mechanical impedance measuring device (“XG-81” produced by Rion),and the vibration spectrum was analyzed with an FFT spectrum analyzer(“FFT analyzer HP3582A” produced by YOKOGAWA Hewlett-Packard, Ltd.).

From the ratio of the loss factor determined thereby and the resonancefrequency with the laminated glass, a graph showing the relation betweensound frequency (Hz) and sound transmission loss (dB) at 20° C. wasplotted, and the minimum sound transmission loss (TL value) around thesound frequency of 2,000 Hz was determined. A higher TL value indicateshigher sound insulation. A TL value of 35 dB or higher was evaluated as“o”, and a TL value of lower than 35 dB was evaluated as “x”. Tables 1to 5 show the results thereof.

(2) Bubble Formation State (Test Method A and Test Method B)

Five sheets of the laminated glass for a bubble formation test wereproduced for each laminated interlayer film, and were left to stand in a50° C. oven for 100 hours. After the standing, the sheets of thelaminated glass were observed by eye in a plan view for the presence orabsence of bubbles and the sizes of the bubbles (test method A). Anotherfive sheets of the laminated glass for a bubble formation test in testmethod B were produced for each laminated interlayer film, and were leftto stand in a 50° C. oven for 30 days. After the standing, the sheets ofthe laminated glass were observed by eye in a plan view for the presenceor absence of bubbles and the sizes of the bubbles (test method B). Fromthe observation results, the bubble formation state was determined basedon the following criteria.

[Criteria of Bubble Formation State]

The bubbles in each of the five sheets of the laminated glass wereapproximated with an ellipse, and the ellipse area was set to the bubbleformation area. The average value of the ellipse areas observed in therespective five sheets of the laminated glass was determined, and theproportion (percentage) of the average value of the ellipses areas(bubble formation areas) to the area of the sheet of the laminated glass(30 cm×15 cm) was determined.

oo: No bubble was observed in all the five sheets of the laminated glass

o: Proportion of average value of ellipse area (bubble formation area)was lower than 5%

Δ: Proportion of average value of ellipse area (bubble formation area)was 5% or higher and lower than 10%

x: Proportion of average value of ellipse area (bubble formation area)was 10% or higher

(3) Penetration Resistance

The surface temperature of sheets of the laminated glass (30 cm(length)×30 cm (width)) used for the penetration resistance test wasadjusted to 23° C. Subsequently, according to JIS R 3212, a rigid spherehaving a mass of 2260 g and a diameter of 82 mm was dropped from aheight of 4 m on the center of each of six sheets of the laminatedglass. The laminated glass was considered to have passed the test if allthe six sheets of the laminated glass prevented the rigid sphere frompenetrating therethrough within five seconds after the rigid sphere hitthe sheets. The laminated glass was considered to have failed the testif three or less sheets of the laminated glass prevented the rigidsphere from penetrating therethrough within five seconds after the rigidsphere hit the sheets. In the case of four sheets, another six sheets ofthe laminated glass were tested again on the penetration resistance. Inthe case of five sheets, another sheet of the laminated glass wastested, and the laminated glass was considered to have passed the testif the other sheet prevented the rigid sphere from penetratingtherethrough within five seconds after the rigid sphere hit the sheet.In the same way, a rigid sphere having a mass of 2260 g and a diameterof 82 mm was dropped from heights of 5 m and 6 m on the center of eachof six sheets of the laminated glass to evaluate the penetrationresistance of the laminated glass.

(4) Measurement of Elastic Modulus G′ by Test Method A

An amount of 100 parts by weight of the polyvinyl acetal resin(polyvinyl acetal resin used for the first layer) in the first layer ofthe interlayer film for a laminated glass in each of the Examples andComparative Examples was mixed with 60 parts by weight of a plasticizerof triethylene glycol di-2-ethylhexanoate (3GO). The mixture wassufficiently kneaded so that a kneaded product was obtained. The kneadedproduct was press-molded in a pressing machine to give a resin film. Ahaving an average thickness of 0.35 mm. The resin film A was left tostand at 25° C. and a relative humidity of 30% for two hours. After thetwo hours of standing, the viscoelasticity of the resin film wasmeasured using ARES-G2 produced by TAINSTRUMENTS. Here, a parallel plateof 8 mm in diameter was used as a geometry. The measurement wasperformed under the conditions of the temperature being decreased from100° C. to −10° C. at a temperature dropping speed of 3° C./min., thefrequency of 1 Hz, and the strain of 1%. The peak temperature of theloss tangent resulting from the measurement was set to the glasstransition temperature Tg(° C.). From the measurement results and theglass transition temperature Tg, the elastic modulus G′(Tg+30) at(Tg+30)° C. and the elastic modulus G′(Tg+80) at (Tg+80)° C. weredetermined. Further, the ratio (G′(Tg+80)/G′(Tg+30)) was calculated.

(5) Measurement of Elastic Modulus G′ by Test Method B

The interlayer films for a laminated glass of the respective Examplesand Comparative Examples were stored in a constant temperature andhumidity room (humidity: 30% (±3%), temperature: 23° C.) for one month.Immediately after the end of the one-month storage, the surface layerswere separated from the intermediate layer to leave the intermediatelayer. In a mold (2 cm in length×2 cm in width×0.76 mm in thickness)arranged between two polyethylene terephthalate (PET) films was placed 1g of the separated intermediate layer. The resulting product waspre-heated at 150° C. and a pressing pressure of 0 kg/cm² for 10minutes, and then press-molded at 80 kg/cm² for 15 minutes. Thepress-molded intermediate layer was put in a hand presser thetemperature of which was set to 20° C. in advance, and the layer waspressed at 10 MPa for 10 minutes for cooling. Subsequently, one PET filmwas removed from the mold arranged between two PET films, and was storedin a constant temperature and humidity room (humidity: 30% (±3%),temperature: 23° C.) for 24 hours. After that, the viscoelasticity ofthe film was measured with ARES-G2 produced by TAINSTRUMENTS. Here, aparallel plate of 8 mm in diameter was used as a geometry. Themeasurement was performed under the conditions of the temperature beingdecreased from 100° C. to −10° C. at a temperature dropping speed of 3°C./min., the frequency of 1 Hz, and the strain of 1%. The peaktemperature of the loss tangent resulting from the measurement was setto the glass transition temperature Tg(° C.). From the measurementresults and the glass transition temperature Tg, the elastic modulusG′(Tg+30) at (Tg+30)° C. and the elastic modulus G′(Tg+80) at (Tg+80)°C. was determined. Further, the ratio (G′(Tg+80)/G′(Tg+30)) wascalculated.

Tables 1 to 5 show the results thereof. In Tables 1 to 5, 3GO and 3GH,which are kinds of plasticizer, respectively represent triethyleneglycol di-2-ethylhexanoate and triethylene glycol di-2-ethylbutyrate.Tables 1 to 5 also show the value of the molecular-weight distribution(weight-average molecular weight Mw/number-average molecular weight Mn)of the polyvinyl acetal resin used for each first layer. Thenumber-average molecular weight Mn of the polyvinyl acetal resin usedfor each first layer was within the range of 50,000 to 500,000. Thenumber-average molecular weight shows the polystyrene-equivalentnumber-average molecular weight by gel permeation chromatography (GPC)measurement.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Formulation of Polyvinyl Averagedegree of 3050 4000 4000 3070 3070 First Layer Butyral polymerization ofPVA Resin Resin Degree of butyralization mol % 64 64 79 63.1 63.1Composition Degree of acetylation mol % 12.5 12.5 0.8 12.1 12.1 forHydroxyl content mol % 23.5 23.5 20.2 24.8 24.8 Intermediate AmountParts by 100 100 100 100 100 Layer Weight Plasticizer Kind 3GO 3GO 3GO3GO 3GO Amount Parts by 60 60 60 70 70 Weight Molecular-weightDistribution 3.0 2.9 3.2 3.0 3.0 Formulation of Polyvinyl Degree ofbutyralization mol % 68.8 68.8 68.8 68.5 68.5 Second and Third ButyralDegree of acetylation mol % 0.8 0.8 0.8 0.8 0.8 Layers Resin Hydroxylcontent mol % 30.4 30.4 30.4 30.7 30.7 Resin Amount Parts by 100 100 100100 100 Composition Weight for Plasticizer Kind 3GO 3GO 3GO 3GO 3GOSurface Layer Amount Parts by 37.5 37.5 37.5 36.5 37.5 Weight Evaluation(1) Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ (2) Bubble formation state intest method A ∘ ∘∘ ∘∘ ∘∘ ∘∘ (2) Bubble formation in test method B ∘ ∘ ∘∘ ∘ (3) Penetration resistance 4 m Passed Passed Passed Passed Passed 5m Passed Passed Passed Passed Passed 6 m Passed Passed Passed PassedPassed (4) Test method A: Glass transition ° C. 1.9 2.1 2.4 4.2 4.2temperature (Tg) (4) Test method A: G′ (Tg + 30) Pa 244000 276000 278000256000 256000 (4) Test method A: G′ (Tg + 80) Pa 180400 231000 249500178960 178960 (4) Test method A: G′ (Tg + 80)/G′ (Tg + 30) 0.74 0.840.90 0.70 0.70 (5) Test method B: Glass transition ° C. −3.1 −4.9 −3.6−3.3 −4.8 temperature (Tg) (5) Test method B: G′ (Tg + 30) Pa 234000236000 253000 221000 231000 (5) Test method B: G′ (Tg + 80) Pa 168300188000 223300 147900 155700 (5) Test method B: G′ (Tg + 80)/G′ (Tg + 30)0.72 0.80 0.88 0.67 0.67 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Formulation ofPolyvinyl Average degree of 3070 3070 3050 3050 3050 First Layer Butyralpolymerization of PVA Resin Resin Degree of butyralization mol % 63.163.1 64.4 64.4 64.4 Composition Degree of acetylation mol % 12.1 12.112.2 12.2 12.2 for Hydroxyl content mol % 24.8 24.8 23.4 23.4 23.4Intermediate Amount Parts by 100 100 100 100 100 Layer WeightPlasticizer Kind 3GO 3GO 3GO 3GO 3GO Amount Parts by 60 60 70 70 60Weight Molecular-weight Distribution 3.0 3.0 3.2 3.2 3.2 Formulation ofPolyvinyl Degree of butyralization mol % 68.5 68.5 68.3 68.3 68.3 Secondand Third Butyral Degree of acetylation mol % 0.8 0.8 0.8 0.8 0.8 LayersResin Hydroxyl content mol % 30.7 30.7 30.9 30.9 30.9 Resin Amount Partsby 100 100 100 100 100 Composition Weight for Plasticizer Kind 3GO 3GO3GO 3GO 3GO Surface Layer Amount Parts by 36.5 37.5 36.5 37.5 36.5Weight Evaluation (1) Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ (2) Bubbleformation state in test method A ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ (2) Bubble formation intest method B ∘ ∘ ∘ ∘ ∘ (3) Penetration resistance 4 m Passed PassedPassed Passed Passed 5 m Passed Passed Passed Passed Passed 6 m PassedPassed Passed Passed Passed (4) Test method A: Glass transition ° C. 4.24.2 1.7 1.7 1.7 temperature (Tg) (4) Test method A: G′ (Tg + 30) Pa256000 256000 250300 250300 250300 (4) Test method A: G′ (Tg + 80) Pa178960 178960 183000 183000 183000 (4) Test method A: G′ (Tg + 80)/G′(Tg + 30) 0.70 0.70 0.73 0.73 0.73 (5) Test method B: Glass transition °C. −1.8 −3.8 −7.3 −8.3 −6.3 temperature (Tg) (5) Test method B: G′ (Tg +30) Pa 230000 220000 238300 222300 220300 (5) Test method B: G′ (Tg +80) Pa 157300 151200 168300 156300 155100 (5) Test method B: G′ (Tg +80)/G′ (Tg + 30) 0.72 0.68 0.69 0.71 0.70 0.70 Ex. 11 Ex. 12 Ex. 13 Ex.14 Ex. 15 Formulation of Polyvinyl Average degree of 3050 3050 3050 30503050 First Layer Butyral polymerization of PVA Resin Resin Degree ofbutyralization mol % 64.4 64 64 77 77 Composition Degree of acetylationmol % 12.2 12.5 12.5 0.8 0.8 for Hydroxyl content mol % 23.4 23.5 23.522.2 22.2 Intermediate Amount Parts by 100 100 100 100 100 Layer WeightPlasticizer Kind 3GO 3GO 3GO 3GO 3GO Amount Parts by 60 65 60 70 55Weight Molecular-weight Distribution 3.2 3.0 3.0 3.2 3.2 Formulation ofPolyvinyl Degree of butyralization mol % 68.3 68.7 68.7 68.6 68.6 Secondand Third Butyral Degree of acetylation mol % 0.8 0.8 0.8 0.8 0.8 LayersResin Hydroxyl content mol % 30.9 30.5 30.5 30.6 30.6 Resin Amount Partsby 100 100 100 100 100 Composition Weight for Plasticizer Kind 3GO 3GO3GO 3GO 3GO Surface Layer Amount Parts by 37.5 38 37.5 36.5 39 WeightEvaluation (1) Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ (2) Bubble formationstate in test method A ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ (2) Bubble formation in testmethod B ∘ ∘ ∘ ∘ ∘ (3) Penetration resistance 4 m Passed Passed PassedPassed Passed 5 m Passed Passed Passed Passed Passed 6 m Passed PassedPassed Passed Passed (4) Test method A: Glass transition ° C. 1.7 1.91.9 6.1 8.1 temperature (Tg) (4) Test method A: G′ (Tg + 30) Pa 250300244000 244000 249000 249000 (4) Test method A: G′ (Tg + 80) Pa 183000180400 180400 181100 181100 (4) Test method A: G′ (Tg + 80)/G′ (Tg + 30)0.73 0.74 0.74 0.73 0.73 (5) Test method B: Glass transition ° C. −7.9−5.1 −4.1 −1.9 −3.9 temperature (Tg) (5) Test method B: G′ (Tg + 30) Pa245300 235500 236500 242100 243800 (5) Test method B: G′ (Tg + 80) Pa175700 171800 171300 168800 171500 (5) Test method B: G′ (Tg + 80)/G′(Tg + 30) 0.72 0.72 0.73 0.72 0.70 0.70

TABLE 2 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Ex. 21 Ex. 22 Formulation ofPolyvinyl Average degree of 3050 3050 3070 3070 4000 4000 4000 FirstLayer Butyral polymerization of PVA Resin Resin Degree of butyralizationmol % 77.3 77.3 72.5 72.5 64.3 64.3 63.4 Composition Degree ofacetylation mol % 0.8 0.8 5.5 5.5 12.5 12.5 12.5 for Hydroxyl contentmol % 21.9 21.9 22 22 23.2 23.2 24.1 Intermediate Amount Parts by 100100 100 100 100 100 100 Layer Weight Plasticizer Kind 3GO 3GO 3GO 3GO3GO 3GO 3GO Amount Parts by 60 65 65 55 70 60 60 Weight Molecular-weightDistribution 2.7 2.7 3.2 3.2 3.0 3.0 2.5 Formulation of Polyvinyl Degreeof butyralization mol % 68.7 68.7 68.2 69 68.9 68.9 68.1 Second andButyral Degree of acetylation mol % 0.8 0.8 0.8 0.8 0.8 0.8 0.8 ThirdLayers Resin Hydroxyl content mol % 30.5 30.5 31 30.2 30.3 30.3 31.1Resin Amount Parts by 100 100 100 100 100 100 100 Composition Weight forPlasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO 3GO Surface Layer Amount Partsby 37.5 37.5 37 38.5 37 37.5 38 Weight Evaluation (1) Sound insulation:TL value ∘ ∘ ∘ ∘ ∘ ∘ ∘ (2) Bubble formation state in test method A ∘∘ ∘∘∘∘ ∘∘ ∘∘ ∘∘ ∘∘ (2) Bubble formation state in test method B ∘ ∘ ∘ ∘ ∘∘ ∘∘∘∘ (3) Penetration resistance 4 m Passed Passed Passed Passed PassedPassed Passed 5 m Passed Passed Passed Passed Passed Passed Passed 6 mPassed Passed Passed Passed Passed Passed Passed (4) Test method A:Glass transition ° C. 5.6 5.6 4.9 4.9 1.9 1.9 3.7 temperature (Tg) (4)Test method A: G′ (Tg + 30) Pa 250000 250000 250500 250500 271000 271000268800 (4) Test method A: G′ (Tg + 80) Pa 179100 179100 181200 181200225800 225800 224700 (4) Test method A: G′ (Tg + 80)/G′ (Tg + 30) 0.720.72 0.72 0.72 0.83 0.83 0.84 (5) Test method B: Glass transition ° C.0.6 −1.4 −3.1 −2.1 −7.1 −4.1 −6.3 temperature (Tg) (5) Test method B: G′(Tg + 30) Pa 240000 230000 225500 215500 265500 245000 232800 (5) Testmethod B: G′ (Tg + 80) Pa 167100 162500 163100 149400 214600 200500191800 (5) Test method B: G′ (Tg + 80)/G′ (Tg + 30) 0.70 0.71 0.72 0.690.81 0.82 0.82 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Ex. 27 Ex. 28 Ex. 29Formulation of Polyvinyl Average degree of 4000 4000 4000 5000 5000 50005000 First Layer Butyral polymerization of PVA Resin Resin Degree ofbutyralization mol % 63.4 79 79 63.9 63.9 77.1 77.1 Composition Degreeof acetylation mol % 12.5 0.8 0.8 12.5 12.5 0.8 0.8 for Hydroxyl contentmol % 24.1 20.2 20.2 23.6 23.6 22.1 22.1 Intermediate Amount Parts by100 100 100 100 100 100 100 Layer Weight Plasticizer Kind 3GO 3GO 3GO3GO 3GO 3GO 3GO Amount Parts by 70 70 60 70 60 70 60 WeightMolecular-weight Distribution 2.5 3.2 3.2 2.5 2.5 2.5 2.5 Formulation ofPolyvinyl Degree of butyralization mol % 68.1 69.1 69.1 68.5 68.5 68.768.7 Second and Butyral Degree of acetylation mol % 0.8 0.8 0.8 0.8 0.80.8 0.8 Third Layers Resin Hydroxyl content mol % 31.1 30.1 30.1 30.730.7 30.5 30.5 Resin Amount Parts by 100 100 100 100 100 100 100Composition Weight for Plasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO 3GOSurface Layer Amount Parts by 36.5 36.5 38 36 37.5 36.5 39 WeightEvaluation (1) Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ ∘ ∘ (2) Bubbleformation state in test method A ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ (2) Bubbleformation state in test method B ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ (3) Penetrationresistance 4 m Passed Passed Passed Passed Passed Passed Passed 5 mPassed Passed Passed Passed Passed Passed Passed 6 m Passed PassedPassed Passed Passed Passed Passed (4) Test method A: Glass transition °C. 3.7 2.4 2.4 3.3 3.3 3.9 3.9 temperature (Tg) (4) Test method A: G′(Tg + 30) Pa 268800 278000 278000 276500 276500 277800 277800 (4) Testmethod A: G′ (Tg + 80) Pa 224700 249500 249500 244400 244400 253200253200 (4) Test method A: G′ (Tg + 80)/G′ (Tg + 30) 0.84 0.90 0.90 0.880.88 0.91 0.91 (5) Test method B: Glass transition ° C. −5.3 −5.1 −7.6−3.7 −6.3 −2.1 −8.1 temperature (Tg) (5) Test method B: G′ (Tg + 30) Pa256800 250000 268400 271500 268000 270300 260900 (5) Test method B: G′(Tg + 80) Pa 208200 217400 233600 235900 234200 242300 230000 (5) Testmethod B: G′ (Tg + 80)/G′ (Tg + 30) 0.81 0.87 0.87 0.87 0.87 0.90 0.88

TABLE 3 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex.4 Ex. 5 Ex. 6 Ex. 7 Formulation of Polyvinyl Average degree of 2300 17002300 2300 1700 2500 2500 First Layer Butyral polymerization of PVA ResinResin Degree of butyralization mol % 64 79 64 64 79 79 79 CompositionDegree of acetylation mol % 12.5 0.8 12.5 12.5 0.8 0.8 0.8 for Hydroxylcontent mol % 23.5 20.2 23.5 23.5 20.2 20.2 20.2 Intermediate AmountParts by 100 100 100 100 100 100 100 Layer Weight Plasticizer Kind 3GO3GO 3GO 3GO 3GO 3GO 3GO Amount Parts by 60 60 70 60 70 70 60 WeightMolecular-weight Distribution 3.5 3.6 3.5 3.5 3.6 3.6 3.6 Formulation ofPolyvinyl Degree of butyralization mol % 68.8 68.8 68.4 68.4 68.8 68.868.8 Second and Butyral Degree of acetylation mol % 0.8 0.8 0.8 0.8 0.80.8 0.8 Third Layers Resin Hydroxyl content mol % 30.4 30.4 30.8 30.830.4 30.4 30.4 Resin Amount Parts by 100 100 100 100 100 100 100Composition Weight for Plasticizer Kind 3GO 3GO 3 GO 3GO 3GO 3GO 3GOSurface Layer Amount Parts by 37.5 37.5 36.5 37.5 36.5 36.5 37.5 WeightEvaluation (1) Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ ∘ ∘ (2) Bubbleformation state in test method A x x x x x x x (2) Bubble formationstate in test method B x x x x x x x (3) Penetration resistance 4 mPassed Passed Passed Passed Passed Passed Passed 5 m Passed PassedPassed Passed Passed Passed Passed 6 m Passed Passed Passed PassedPassed Passed Passed (4) Test method A: Glass transition ° C. 1.8 2.41.8 1.8 2.4 2.4 2.4 temperature (Tg) (4) Test method A: G′ (Tg + 30) Pa236500 245000 236500 236500 245000 221500 221500 (4) Test method A: G′(Tg + 80) Pa 142000 105000 142000 142000 105000 137900 137900 (4) Testmethod A: G′ (Tg + 80)/G′ (Tg + 30) 0.60 0.43 0.60 0.60 0.43 0.62 0.62(5) Test method B: Glass transition ° C. −3.2 −4.6 −4.2 −5.7 −6.6 −3.6−5.6 temperature (Tg) (5) Test method B: G′ (Tg + 30) Pa 226500 225000211500 201500 220000 195500 205500 (5) Test method B: G′ (Tg + 80) Pa131500 94200 127000 114900 88800 118800 125500 (5) Test method B: G′(Tg + 80)/G′ (Tg + 30) 0.58 0.42 0.60 0.57 0.40 0.61 0.61

TABLE 4 Ex. 30 Ex. 31 Ex. 32 Ex. 33 Formulation of Polyvinyl Averagedegree of 3050 3050 3050 4000 First Layer Butyral polymerization of PVAResin Resin Degree of butyralization mol % 64.4 73.4 78 64.3 CompositionDegree of acetylation mol % 12.2 5.6 1.2 12.5 for Hydroxyl content mol %23.4 21 20.8 23.2 Intermediate Proportion of carboxyl mol % — — — —Layer acid modification Amount Parts by 100 100 100 100 WeightPlasticizer Kind 3GH 3GH 3GH 3GH Amount Parts by 60 60 60 60 WeightMolecular-weight Distribution 3.2 3.1 3.2 3.2 Sodium Amount Parts by — —— — Tetraborate Na Weight Formulation of Polyvinyl Degree ofbutyralization mol % 68.3 68.3 68.3 68.3 Second and Third Butyral Degreeof acetylation mol % 0.8 0.8 0.8 0.8 Layers Resin Hydroxyl content mol %30.9 30.9 30.9 30.9 Resin Amount Parts by 100 100 100 100 CompositionWeight for Plasticizer Kind 3GH 3GH 3GH 3GH Surface Layer Amount Partsby 37.5 37.5 37.5 37.5 Weight Evaluation (1) Sound insulation: TL value∘ ∘ ∘ ∘ (2) Bubble formation state in test method A ∘∘ ∘∘ ∘∘ ∘∘ (2)Bubble formation in test method B ∘ ∘ ∘ ∘ (3) Penetration resistance 4 mPassed Passed Passed Passed 5 m Passed Passed Passed Passed 6 m PassedPassed Passed Passed (4) Test method A: Glass transition temperature(Tg) ° C. 2.1 5.3 6.3 2.3 (4) Test method A: G′ (Tg + 30) Pa 254200253200 243600 256200 (4) Test method A: G′ (Tg + 80) Pa 186600 184500175200 215000 (4) Test method A: G′ (Tg + 80)/G′ (Tg + 30) 0.73 0.730.72 0.84 (5) Test method B: Glass transition temperature (Tg) ° C. −1.7−1.5 1.2 −1.6 (5) Test method B: G′ (Tg + 30) Pa 244200 233200 218600221200 (5) Test method B: G′ (Tg + 80) Pa 174400 167600 157200 179000(5) Test method B: G′ (Tg + 80)/G′ (Tg + 30) 0.71 0.72 0.72 0.81 Ex. 34Ex. 35 Ex. 36 Ex. 37 Formulation of Polyvinyl Average degree of 23101715 3020 1800 First Layer Butyral polymerization of PVA Resin ResinDegree of butyralization mol % 64.4 78 64.3 64.9 Composition Degree ofacetylation mol % 12.2 0.8 13.2 12.6 for Hydroxyl content mol % 23.421.2 22.5 21.3 Intermediate Proportion of carboxyl mol % — — — 1.2 Layeracid modification Amount Parts by 100 100 100 100 Weight PlasticizerKind 3GO 3GO 3GO 3GO Amount Parts by 60 60 60 60 Weight Molecular-weightDistribution 3.2 3.1 2.8 3.2 Sodium Amount Parts by 0.12 0.12 0.12 —Tetraborate Na Weight Formulation of Polyvinyl Degree of butyralizationmol % 68.3 68.3 68.3 68.3 Second and Third Butyral Degree of acetylationmol % 0.8 0.8 0.8 0.8 Layers Resin Hydroxyl content mol % 30.9 30.9 30.930.9 Resin Amount Parts by 100 100 100 100 Composition Weight forPlasticizer Kind 3GO 3GO 3GO 3GO Surface Layer Amount Parts by 37.5 37.537.5 37.5 Weight Evaluation (1) Sound insulation: TL value ∘ ∘ ∘ ∘ (2)Bubble formation state in test method A ∘∘ ∘∘ ∘∘ ∘∘ (2) Bubble formationin test method B ∘ ∘ ∘ ∘ (3) Penetration resistance 4 m Passed PassedPassed Passed 5 m Passed Passed Passed Passed 6 m Passed Passed PassedPassed (4) Test method A: Glass transition temperature (Tg) ° C. 0.1 2.42.0 1.2 (4) Test method A: G′ (Tg + 30) Pa 283605 279855 233100 242400(4) Test method A: G′ (Tg + 80) Pa 201653 190145 216000 169100 (4) Testmethod A: G′ (Tg + 80)/G′ (Tg + 30) 0.71 0.68 0.93 0.70 (5) Test methodB: Glass transition temperature (Tg) ° C. −8.9 −3.6 −6.0 −7.8 (5) Testmethod B: G′ (Tg + 30) Pa 258605 253855 197100 230400 (5) Test method B:G′ (Tg + 80) Pa 177400 168700 180300 155000 (5) Test method B: G′ (Tg +80)/G′ (Tg + 30) 0.69 0.66 0.91 0.67

TABLE 5 Ex. 38 Ex. 39 Ex. 40 Ex. 41 Ex. 42 Ex. 43 Ex. 44 Formulation ofPolyvinyl Average degree of 3050 3050 3080 3020 3040 3200 3400 FirstLayer Butyral polymerization of Resin Resin PVA Composition Degree ofmol % 64.4 64.1 64.8 65.1 70 59.2 54.1 for butyralization IntermediateDegree of mol % 12.2 12.7 11.7 12.1 8.5 19 23 Layer acetylation Hydroxylcontent mol % 23.4 23.2 23.5 22.8 21.5 21.8 22.9 Amount Parts by 100 100100 100 100 100 100 Weight Plasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO 3GOAmount Parts by 60 60 60 60 60 60 60 Weight Molecular-weightDistribution 1.2 4.3 5.4 6.4 1.5 3.8 4.6 Sodium Amount Parts by — — — —— — — Tetraborate Weight Na Formulation Polyvinyl Degree of mol % 68.368.3 68.3 68.3 68.3 68.3 68.3 of Second Butyral butyralization and ThirdResin Degree of mol % 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Layers acetylationResin Hydroxyl content mol % 30.9 30.9 30.9 30.9 30.9 30.9 30.9Composition Amount Parts by 101 102 103 104 105 106 107 for WeightSurface Plasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GO 3GO Layer Amount Partsby 37.5 37.5 37.5 37.5 37.5 37.5 37.5 Weight Evaluation (1) Soundinsulation: TL value ∘ ∘ ∘ ∘ ∘ ∘ ∘ (2) Bubble formation state in test ∘∘∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ method A (2) Bubble formation in test method B ∘ ∘ ∘ ∘∘ ∘ ∘ (3) Penetration resistance 4 m Passed Passed Passed Passed PassedPassed Passed 5 m Passed Passed Passed Passed Passed Passed Passed 6 mPassed Passed Passed Passed Passed Passed Passed (4) Test method A:Glass ° C. 1.3 1.2 1.5 0.7 −0.3 −0.1 1.1 transition temperature (Tg) (4)Test method A: G′ Pa 245600 239800 254100 239900 248800 249700 256900(Tg + 30) (4) Test method A: G′ Pa 176832 170258 190575 165531 166696169796 179830 (Tg + 80) (4) Test method A: G′ 0.72 0.71 0.75 0.69 0.670.68 0.70 (Tg + 80)/G′ (Tg + 30) (5) Test method B: Glass ° C. −3.0 −2.5−2.0 −2.8 −3.8 −3.6 −2.4 transition temperature (Tg) (5) Test method B:G′ Pa 233600 224800 238300 227300 226300 228700 225900 (Tg + 30) (5)Test method B: G′ Pa 165900 155100 174000 150000 147100 148700 153600(Tg + 80) (5) Test method B: G′ 0.71 0.69 0.73 0.66 0.65 0.65 0.68 (Tg +80)/G′ (Tg + 30) Comp. Comp. Comp. Comp. Comp. Ex. 45 Ex. 46 Ex. 8 Ex. 9Ex. 10 Ex. 11 Ex. 12 Formulation of Polyvinyl Average degree of 34803150 2000 2300 2300 2300 2500 First Layer Butyral polymerization ofResin Resin PVA Composition Degree of mol % 71 74.5 64 64.1 72 64.2 79for butyralization Intermediate Degree of mol % 7.5 3.1 12.5 12.3 5.412.5 0.8 Layer acetylation Hydroxyl content mol % 21.5 22.4 23.5 23.622.6 23.3 20.2 Amount Parts by 100 100 100 100 100 100 100 WeightPlasticizer Kind 3GO 3GO 3GO 3GO 3GO 3GH 3GH Amount Parts by 60 60 60 6060 60 60 Weight Molecular-weight Distribution 2.5 6.3 2.7 2.8 2.8 3.63.6 Sodium Amount Parts by — — — — — — — Tetraborate Weight NaFormulation Polyvinyl Degree of mol % 68.3 68.3 68.4 68.4 68.4 68.8 68.8of Second Butyral butyralization and Third Resin Degree of mol % 0.8 0.80.8 0.8 0.8 0.8 0.8 Layers acetylation Resin Hydroxyl content mol % 30.930.9 30.8 30.8 30.8 30.4 30.4 Composition Amount Parts by 108 109 100100 100 100 100 for Weight Surface Plasticizer Kind 3GO 3GO 3GO 3GO 3GO3GH 3GH Layer Amount Parts by 37.5 37.5 36.5 37.5 37.5 37.5 37.5 WeightEvaluation (1) Sound insulation: TL value ∘ ∘ ∘ ∘ ∘ ∘ ∘ (2) Bubbleformation state in ∘∘ ∘∘ x x x x x test method A (2) Bubble formation intest method B ∘ ∘ x x x x x (3) Penetration resistance 4 m Passed PassedPassed Passed Passed Passed Passed 5 m Passed Passed Passed PassedPassed Passed Passed 6 m Passed Passed Passed Passed Passed PassedPassed (4) Test method A: Glass ° C. 0.3 0.3 1.8 1.8 1.8 1.8 1.3transition temperature (Tg) (4) Test method A: G′ Pa 247500 246300236500 241000 243200 222400 225600 (Tg + 30) (4) Test method A: G′ Pa173250 172410 142000 147000 145200 135000 145200 (Tg + 80) (4) Testmethod A: G′ 0.70 0.70 0.60 0.61 0.60 0.61 0.64 (Tg + 80)/G′ (Tg + 30)(5) Test method B: Glass ° C. −3.2 −3.2 −8.2 −6.2 −7.8 −4.2 −5.7transition temperature (Tg) (5) Test method B: G′ Pa 230500 230300208500 213000 238200 213900 218100 (Tg + 30) (5) Test method B: G′ Pa156700 156600 119400 124200 138600 127700 137100 (Tg + 80) (5) Testmethod B: G′ 0.68 0.68 0.57 0.58 0.58 0.60 0.63 (Tg + 80)/G′ (Tg + 30)

Tables 1 to 5 show the ratio (G′(Tg+80)/G′(Tg+30)) of the resin film Bdetermined by measuring the elastic modulus G′ of the resin film B(first layer) containing the polyvinyl acetal resin and the plasticizerwhich constituted the first layer of the interlayer film for a laminatedglass in each of the Examples and Comparative Examples according to theformulations shown in Tables 1 to 5, after the plasticizer was migratedbetween the layers of the laminated interlayer film. The ratio(G′(Tg+80)/G′(Tg+30)) of the resin film B was almost the same as theratio (G′(Tg+80)/G′(Tg+30)) of the resin film A that contained 100 partsby weight of the polyvinyl acetal resin in the first layer and 60 partsby weight of 3GO.

EXPLANATION OF SYMBOLS

-   1 Interlayer film-   2 First layer-   2 a One face-   2 b The other face-   3 Second layer-   3 a Outer surface-   4 Third layer-   4 a Outer surface-   11 Laminated glass-   12 First laminated-glass component-   13 Second laminated-glass component

1. An interlayer film for a laminated glass, comprising a first layerthat contains a polyvinyl acetal resin and a plasticizer, and a secondlayer that contains a polyvinyl acetal resin and a plasticizer and islaminated on one face of the first layer, wherein in the case ofmeasuring viscoelasticity of a resin film formed from the first layer,the resin film, having a glass transition temperature of Tg(° C.), hasan elastic modulus of G′(Tg+80) at (Tg+80)° C. and an elastic modulus ofG′(Tg+30) at (Tg+30)° C., and provides a ratio (G′(Tg+80)/G′(Tg+30)) of0.65 or higher.
 2. An interlayer film for a laminated glass, comprisinga first layer that contains a polyvinyl acetal resin and a plasticizer,and a second layer that contains a polyvinyl acetal resin and aplasticizer and is laminated on one face of the first layer, wherein inthe case of measuring viscoelasticity of a resin film formed with 100parts by weight of the polyvinyl acetal resin contained in the firstlayer and 60 parts by weight of a plasticizer of triethylene glycoldi-2-ethylhexanoate (3GO), the resin film, having a glass transitiontemperature of Tg(° C.), has an elastic modulus of G′(Tg+80) at (Tg+80)°C. and an elastic modulus of G′(Tg+30) at (Tg+30)° C., and provides aratio (G′(Tg+80)/G′(Tg+30)) of 0.65 or higher.
 3. The interlayer filmfor a laminated glass according to claim 1 or 2, wherein the elasticmodulus G′(Tg+30) is 200,000 Pa or higher.
 4. The interlayer film for alaminated glass according to claim 1 or 2, wherein the polyvinyl acetalresin in the first layer has a degree of acetylation of 8 mol % orhigher.
 5. The interlayer film for a laminated glass according to claim1 or 2, wherein the polyvinyl acetal resin in the first layer has adegree of acetylation of lower than 8 mol % and a degree ofacetalization of 68 mol % or higher.
 6. The interlayer film for alaminated glass according to claim 1 or 2, wherein the polyvinyl acetalresin in the first layer has a molecular-weight distribution(weight-average molecular weight Mw/number-average molecular weight Mn)of 6.5 or lower.
 7. The interlayer film for a laminated glass accordingto claim 6, wherein the polyvinyl acetal resin in the first layer has amolecular-weight distribution (weight-average molecular weightMw/number-average molecular weight Mn) of 2.5 to 3.2.
 8. The interlayerfilm for a laminated glass according to claim 1 or 2, wherein the firstlayer has 50 parts by weight or more of the plasticizer for each 100parts by weight of the polyvinyl acetal resin.
 9. The interlayer filmfor a laminated glass according to claim 8, wherein the first layer has55 parts by weight or more of the plasticizer for each 100 parts byweight of the polyvinyl acetal resin.
 10. The interlayer film for alaminated glass according to claim 9, wherein the polyvinyl acetal resinin the first layer contains 30 mol % or lower of a hydroxyl group. 11.The interlayer film for a laminated glass according to claim 1 or 2,further comprising a third layer that contains a polyvinyl acetal resinand a plasticizer and is laminated on the other face of the first layer.12. The interlayer film for a laminated glass according to claim 11,wherein the polyvinyl acetal resin in the first layer has a degree ofacetylation of 8 mol % or higher.
 13. The interlayer film for alaminated glass according to claim 11, wherein the polyvinyl acetalresin in the first layer has a degree of acetylation of lower than 8 mol% and a degree of acetalization of 68 mol % or higher.
 14. Theinterlayer film for a laminated glass according to claim 12, wherein anamount of the plasticizer for each 100 parts by weight of the polyvinylacetal resin in the first layer is larger than an amount of theplasticizer for each 100 parts by weight of the polyvinyl acetal resinin each of the second layer and the third layer.
 15. The interlayer filmfor a laminated glass according to claim 14, wherein the polyvinylacetal resin in each of the first layer, the second layer and the thirdlayer includes a polyvinyl butyral resin, and the plasticizer in each ofthe first layer, the second layer and the third layer includes at leastone compound selected from the group consisting of triethylene glycoldi-2-ethylbutyrate, triethylene glycol di-2-ethylhexanoate, andtriethylene glycol di-n-heptanoate.
 16. The interlayer film for alaminated glass according to claim 1 or 2, wherein the polyvinyl acetalresin in the first layer includes a carboxylic acid-modified polyvinylacetal resin.
 17. The interlayer film for a laminated glass according toclaim 1 or 2, wherein the first layer contains a compound that has aboron atom.
 18. The interlayer film for a laminated glass according toclaim 17, wherein the compound that has a boron atom includes at leastone compound selected from the group consisting of sodium tetraborate,potassium tetraborate, and boric acid.
 19. A laminated glass comprisingfirst laminated-glass component and second laminated-glass component,and an interlayer film sandwiched between the first laminated-glasscomponent and the second laminated-glass component, wherein theinterlayer film is the interlayer film for a laminated class accordingto claim 1 or 2.